Fish in aspic (Ryba Zalivnaya)

It's a very old and very traditional Yiddish dish. It was made by my mom according to a recipe from her mother-in-law Ronya.

1 (6-lb) whole bass fish (with skin), gutted and cleaned, head and tail left intact. If you don't have a long pan for cooking, cut into a big pieces (see the picture).
1 large onion, cut into thing round slices
1 tablespoon olive oil
2 carrots, coarsely chopped
1 small red beets, peeled and cut into 1/4-inch round pieces
cold water
2 bay leaves
1/4 teaspoon whole black peppercorns
Salt to taste
1 package of gelatin (2 1/2 teaspoons (7g) unflavored gelatine)
3-4 fresh parsley sprigs for decoration

Wash bass inside and out and sprinkle inside with salt.

Pour olive oil on a frying pan. Heat the skillet on high until the oil is very hot but not smoking. Add half of the onions all at once and reduce the heat to low-medium low. Using a spatula, turn (toss) the onions so that all the pieces get some oil on them. Continue to turn the onions with the spatula about every 2 to 3 minutes. Cook until onion is translucent. Remove the onions, turn off the heat and cool a little bit.

Place second half of the onions, carrots, and beets on the bottom of the pan. Add fried onions, bay leaves, and peppercorns. Place fish pieces on a top of vegetables. Add water enough to cover all pieces. Bring to boil, partially covered, over the high heat. Check for salt and pepper (Add as need it.) Reduce the heat and simmer for 20-30 minutes.

Pour 1 cup of broth through a sieve into a small bowl. Add gelatin and mix very well.

Lift fish pieces out of broth and drain well, then transfer to a large long shallow fish plate and chill for 10-15 minutes. Pour gelatine mixture over the fish. If it's not enough to cover all fish use liquid from the pan. Use carrots and parsley to decorate a dish. Chill fish, uncovered. Put in refrigerator for several hours. Take out before serving.