Cauliflower Baked in Cheese


1 cauliflower, broken in flowerets
1 T safflower oil
1 med onion
1 lb ripe tomatoes, sliced
½ C Gruyere or Mozzarella cheese, grated
1/4 C fresh Parmesan cheese
1/4 C toasted sesame seeds

Steam cauliflower 5-10 min. Saute onion until tender. Add tomato and cook uncovered 10-15 min. Add cauliflower and toss together. Fill 2-quart baking dish. Toss together cheeses and sesame seeds and spread over top. Bake 375 ° for 30 min, until top begins to brown.