Line the bottom of a springform tin with aluminium foil and set aside.
Heat oil in a frypan and sautee the mushrooms, zucchini, capsicum, onions and garlic until soft. Drain off any liquid.
Preheat the oven to 175 degrees C.
In a large bowl mix eggs and ricotta. Mix in the spinach, feta, parsley, thyme and season with salt and pepper. Stir into the mushroom mixture.
Pour the filling into the prepared tin and bake in the preheated oven for 45-55 minutes until the edges are lightly browned. Use a knife to check if the quiche is cooked through. Stick the knife into the middle if no filling sticks to the knife the quiche is ready.
Leave the quiche to stand for 10 minutes then remove the edges of the springform tin and lay tomatoes on top.