- Making your own aji amarillo paste, if possible, gives the mashed potatoes a fruitier, brighter, and more complex flavor.
- Mashing the potatoes while warm and chilling after ensures a soft and pliable mash to stir in the seasonings.
If there’s one dish that most Americans really should know but don’t, it’s causa. It’s everything Americans love—mashed potatoes, tuna (or chicken, or some similar) salad, and potato salad—all compressed into one easy make-ahead casserole. It could be the ultimate all-American potluck dish, except that it’s entirely Peruvian.
I first learned of causa many years ago when a Peruvian cook I worked with named Felipe would sometimes make it for the staff. Years later I took a trip to Peru and ate several examples of it there. What becomes clear about causa after eating it just a few times is that it can come in many forms, but a few features are constant: Causa is always served cold; causa always features a top and bottom layer of mashed potatoes that are seasoned with lime juice and aji amarillo (a spicy Peruvian chile pepper); and causa always contains a mayonnaise-y salad.
Beyond those basic qualities, causa can vary widely. For one thing, as already mentioned, the salad in the middle can be made with a wide range of meats or seafood—tuna, chicken, crab, or some other white meat or seafood—though tuna and chicken are the most common. And what’s in that salad can vary quite a bit, too. It could be as simple as the meat tossed with some minced onion and mayonnaise, but it could also include peas and carrots, or a layer of sliced avocado, or diced shrimp, or something else. Sometimes you’ll see black olives, or tomatoes, or chile peppers, or slices of hardboiled egg. And sometimes causa is served as a large casserole (making it the perfect potluck dish), while at other times it’s made into more elegant individual portions by stacking the layers inside a ring mold.
That’s the best part about causa: You can and should have a lot of fun with it. Just use the basic template as your guide and feel free to play around with the rest.
The first step is to mash some potatoes. In Peru, they use a variety of yellow potato that we don’t have in the United States (nor do we have most of the other hundreds upon hundreds of potatoes native to Peru). Anyone not in Peru will have to use what they can find. I have a Peruvian friend who says russets are the best option stateside, but I’ve also tested the recipe with Yukon golds, and they work well, too.
Next, you will need aji amarillo paste, which is made from one of Peru’s most popular chile peppers. You can buy the paste premade in well-stocked Latin American grocers, but even better, if you can find it, is to start with frozen whole aji amarillos; they’d be in the freezer section of a very, very well-stocked Latin American grocer.
Simply steep the frozen peppers in boiling water for a few minutes to soften them, then trim away their stems and seeds. Put the pepper flesh in a blender and let it run until the purée becomes uniform and smooth; there’s no need to add water or any other liquid. The paste made from frozen peppers is fruitier, brighter, and more complex than the one in the jar, so it’s worth making if you can find the frozen peppers.
To make the mashed potatoes, cook the potatoes either by baking, microwaving, or boiling them. Pass the cooked potato flesh through a ricer or food mill, add the aji amarillo paste, lime juice, and oil, and stir it in until the potatoes are an even yellow hue. This should be done while the potatoes are still somewhat hot, since they won’t mash well once fully cooled. Only after you’ve mixed everything together should the potatoes be chilled in the fridge.
For the filling, my recipe gives the option of either tuna or chicken, but you could of course use another appropriate meat, such as crab. Whichever you use, mix it with finely minced white onion and enough mayonnaise to make it soft and spreadable. Add-ins are up to you. Cooked peas and carrots are a common choice.
To form the causa, you can either make a large one in a casserole dish, or smaller individual ones. Start by spreading out an even layer of the mashed potatoes on the bottom of a casserole dish or on a plate, using a ring mold around it to help keep a cylindrical form. Next, add the salad filling, plus anything else you’d like to include. I show diced shrimp here with the tuna salad in the casserole dish, and thinly sliced avocado with the chicken salad on the plate; you could put the avocado with the tuna, or add olives or whatever else you may fancy.
On top of that goes the final layer of mashed potatoes. To finish it, you can garnish the top of the causa with whatever you think looks good, making little designs with additional ingredients, such as black olives, diced avocado, pieces of tomato, a drizzle of mayo, and a sprinkling of fresh herbs.
Once it’s assembled, a casserole-style causa can be kept refrigerated overnight, making it an excellent make-ahead dish for potlucks and such. It’s not an American dish, but it’ll fit right in next to the onion dip and mac and cheese.
- 4 1/4 pounds (2kg) russet or Yukon gold potatoes (about 6 russets or 8 Yukon golds)
- Frozen aji amarillo peppers or a jar of aji amarillo paste(see notes)
- 2/3 cup (160ml) vegetable or corn oil
- 4 to 5 tablespoons (60 to 75ml) fresh lime juice from 2 limes
- Kosher salt
- Two 5-ounce (140g) cans tuna in olive oil, drained (or 10 ounces/280g shredded roast chicken meat)
- One-quarter of a 12-ounce white onion, finely minced (about 1/3 cup minced)
- 1/2 cup homemade or store-bought mayonnaise (4 ounces/110g), plus more if desired
- Diced poached shrimp, sliced avocado, pitted black olives, minced fresh herbs (such as chives), diced or thinly sliced seeded tomatoes, or other ingredients to garnish your causa
Bake, microwave, or boil the potatoes until you can slide a fork easily through them. Let cool just slightly, then scoop out the flesh and, using a ricer or food mill, mash the potatoes into a large heatproof mixing bowl.
Meanwhile, if using frozen aji amarillo peppers, in a medium saucepan, bring water to a boil. Add frozen peppers, remove from heat, and let steep 5 minutes. Stem and seed peppers (wear gloves if possible, as peppers are spicy), then blend the flesh without any additional liquid until a smooth and even paste forms. (Extra aji amarillo paste can be stored in the refrigerator with a layer of oil poured on top for up to 2 weeks.)
Add 3 tablespoons (45ml) homemade or store-bought aji amarillo paste to potatoes, along with the oil, and 4 tablespoons (60ml) lime juice. Season with salt. Fold together until evenly incorporated, then taste. Add the remaining 1 tablespoon (15ml) lime juice, if desired. Press plastic directly against the surface of the mashed potatoes and refrigerate until chilled.
In a medium mixing bowl, stir together tuna (or chicken), onion, and mayonnaise until evenly mixed. Season with salt. Keep chilled.
When ready to assemble, lay down an even roughly 1-inch layer of mashed potatoes in the bottom of a 2-quart casserole dish; alternatively, you can build the causa on individual serving plates using a ring mold to help form it into a neat cylinder.
Next add a roughly 1-inch thick layer of the tuna or chicken salad. If adding other ingredients like diced, poached shrimp or diced avocado, layer them in either above or below the tuna or chicken salad.
Top with a final layer of the mashed potatoes. You can garnish the top of your causa with whatever you want, including pieces of black olive, sliced or diced tomato, fresh minced herbs, sliced or diced avocado, pieces of shrimp, et cetera.
Keep chilled until ready to serve. The causa in the casserole can be refrigerated overnight.
Ricer or food mill, 2-quart casserole dish or ring molds
You can find frozen aji amarillo peppers (in 15 oz bags) in the freezer section of a well-stocked Latin American grocer; 10.5 oz jars of aji amarillo paste are also found at Latin American grocers and online as well.