Tomato Casserole (Tomates en Charlotte)

Olive oil
1 yellow onion
3 tomatoes
Salt and pepper
Spanish (red) onion
3 boiled, peeled potatoes
Grated cheese

Lightly color a medium-size, peeled, finely minced onion in 1/2 cup olive oil. Spread one-third of the hot, oniony oil in the bottom of an earthenware (nonmetal) baking dish. Cover with a layer of tomato slices (approx 1 medium-size tomato), season with salt and pepper and 1 teaspoon grated red (Spanish) onion. Cover the tomatoes with a layer of boiled (but still firm) peeled, sliced potatoes. Season lightly with salt and pepper plus a thin sprinkle of grated cheese. make a second layer of onion, tomato slices, red onion, and potato. Finish with a layer of tomatoes and cooked, minced onion. Sprinkle with remaining olive oil and bake 30 minutes in a 350-degree oven.