How to Make It
In a medium saucepan, combine the tomatoes and their juices with the onion, lemon, sugar, peppercorns, cloves and bay leaf and bring to a boil over moderately high heat. Cover and simmer over moderately low heat for 20 minutes.
Strain the tomatoes through a fine mesh sieve set over a large heatproof measuring cup, pressing on the solids to extract as much juice as possible; you should have about 1 1/2 cups. Stir in the vinegar and season with salt. Stir the gelatin into the hot stock until completely dissolved. Then whisk the mixture into the hot tomato juice. Let cool.
Line the sides of a nonreactive 9-inch ring mold with the slices of egg, and line the bottom with a ring of sliced olives. Place the mold on a small baking sheet and fill the mold with the flaked salmon, trying to not disturb the eggs and olives. Carefully pour in the tomato juice, filling the mold to the top. Cover with plastic wrap and refrigerate overnight or for at least 12 hours.
Unmold the ring onto a chilled plate, cut into slices and serve.
The aspic can be refrigerated for up to 3 days.