Stuffed tomatoes with mushrooms, parmesan and spinach

large beef tomatoes

dried porcini

olive oil, for frying

packs spinach

flat mushrooms, sliced into rough cubes

garlic, finely chopped

sprig thyme, stalks removed, leaves finely chopped

lemons, juice only

ricotta cheese

parmesan, , or vegetarian Italian hard cheese, freshly grated

good pinch of freshly grated nutmeg

egg yolk, beaten

black pepper

French mustard

white wine vinegar

olive oil

small handful basil