Drain the crab meat. Peel the grapefruit so that the white skin is completely removed. Remove the fillets with a sharp knife between the parting skins. Collect the juice and press it out of the parting skins. Cut the fillets into cubes. Wash the chives, shake dry and cut into fine rolls
Peel and chop the onion and shallot. Mix with grapefruit cubes and crab meat. Wash lemon, grate dry, finely grate peel. Halve the lemon, squeeze the juice and mix it with the grapefruit juice and lemon peel into the crab mixture
Add olive oil and chive rolls, except for something to garnish. Season to taste with salt and pepper. Divide the mixture into 20 glasses, cover and chill
Stir tarama smooth. Whip cream until stiff, fold in tarama. Pour the mixture into a piping bag with a star-shaped spout, garnish the glass with the tamara cream, sprinkle with the remaining chives and serve