Blanch tomatoes for 1-2 minutes and remove skin.
Halve, removing seeds and inner stem. Puree. Mix with vodka or gin. Beat egg white until medium-stiff.
Fold egg white into tomato-vodka mixture and season with salt and pepper. Freeze in a sorbet or ice cream machine according to directions. Slice avocados in half and remove the pits. Place a scoop of sorbet in every avocado half and serve immediately.