Pour the tomatoes into a sieve, drain, collect the oil and measure 4 tablespoons. Finely dice the tomatoes. Mix vinegar, salt, pepper and sugar. Fold in 4 tbsp. tomato oil.
Halve the melon and cut into slices. Cut the flesh from the skin and remove the seeds. Dice the flesh. Clean and wash the radishes and cut into very fine strips. Wash parsley, shake dry, pluck off leaves and chop finely.
Mix melon, parsley and dressing and fold in radishes loosely. Serve.