Peruvian Causa - cooking recipe

Ingredients

8 russet potatoes, peeled
1/2 cup vegetable oil, or as needed
2 tablespoons minced aji amarillo
salt and ground black pepper to taste
2 (5 ounce) cans tuna, drained
1 small red onion, diced small
1/2 cup mayonnaise, divided
2 avocados, cut into thin strips
3 hard-boiled eggs, thinly sliced

Preparation

Place potatoes into a large pot and cover with salted water; bring to a boil. Reduce heat to medium-low and simmer until tender, about 20 minutes. Drain.
Mash potatoes with a ricer or hand mixer until smooth. Gradually stir in oil until potatoes come together; add aji amarillo, salt, and pepper. Cool potato mixture in the refrigerator, about 20 minutes.
Stir tuna, onion, and 1/4 cup mayonnaise together in a bowl.
Line a casserole dish with plastic wrap. Spread 1/2 the potato mixture on the bottom of the dish. Spread 2 tablespoons mayonnaise over the potatoes, spread the tuna mixture over the mayonnaise, and place the avocado slices in a single layer on top of the tuna mixture. Spread the remaining 1/2 of potato mixture over the avocados, and top with remaining 2 tablespoons mayonnaise. Place sliced eggs over the top. Cover casserole dish with plastic wrap and refrigerate until firm, about 30 minutes.
Invert casserole dish onto a serving dish or baking sheet to remove potato casserole from dish. Remove plastic wrap and cut casserole into squares.