To make simple tomato aspic, put tomato pulp and onions in a pan, mash them well and bring the mixture to a boil. Stir the mixture well in dissolved gelatin and pour the ingredients into a non-stick loaf pan. Chill the mixture until firm, turn it out and slice.
Gather 1 1/2 pounds of plum tomatoes, 3 minced garlic cloves, 1 envelope unflavored gelatin, 3 tablespoons of fresh minced parsley or basil or both and 1 small, minced hot red pepper or chili pepper flakes. Also gather salt and 1 tablespoon of extra virgin olive oil.
Cut the tomatoes in half and squeeze the tomato juice into a sieve over a small bowl to extract seeds and juice. Reserve the pulp and the liquid after sieving.
Use a food processor to puree the tomatoes and remove the skin. Pour the reserved juice into the pulp and sprinkle gelatin over the tomato pulp. Use a medium-sized bowl to heat the pulp and bring it to a boil. Add the boiled ingredients into the softened gelatin and stir until all the gelatin dissolves.
Add the remaining tomato pulp, pepper, extra virgin olive oil, garlic and basil. Put the mixture into a partially-oiled cup mold and allow it to rest for about three hours. Unmold and sprinkle some virgin olive oil on the top.