Mix starch, flour and baking powder. Add the egg, egg yolk and approx. 200 ml water and mix to a smooth dough with the whisks of the hand mixer. Let the dough swell for about 20 minutes
In the meantime clean and slice the tomatoes. Peel onions and cut into rings. Season vinegar with salt, pepper and sugar. Fold in oil drop by drop. Mix tomatoes, onions and vinaigrette. Clean the cauliflower, cut into florets, wash and cook in boiling salted water for about 5 minutes. Wash herbs, dab dry and remove leaves. Cut the herbs finely, except for a few leaves for garnishing. Mix mayonnaise, sour cream and herbs. Season to taste with salt and pepper.
Lift out the cauliflower and drain well. Grate parmesan finely and stir into the tempura dough with approx. 1/2 tsp salt. Pull the cauliflower florets through the dough and fry in portions in hot oil for 3-4 minutes. Remove with a ladle and let it drip off briefly on kitchen paper.
Arrange cauliflower and tomato salad on plates. Add the herb remoulade. Garnish with basil and parsley leaves