Peel onion and chop very finely. Heat 1 tablespoon of olive oil in a saucepan, fry the onion and thyme in it. Deglaze with broth, bring to the boil and stir in polenta. Simmer at medium heat stirring constantly for about 3 minutes.
Turn off the heat and let the polenta swell for about 10 minutes. Then spread into a greased ovenproof dish and let it cool down. In the meantime, peel and finely chop the garlic. Clean, wash and dice the peppers.
Clean, wash and cut the spring onions into rings. Wash, clean, quarter, seed and dice the tomatoes. Zucchini wash, clean and cut into fine sticks. Heat the remaining oil in a large frying pan.
Fry the garlic, spring onions, bell peppers and courgette for about 3 minutes, turning them over. Add tomatoes and steam for another minute. Season with salt, pepper, paprika and cumin. Remove from the heat and allow to cool slightly.
Meanwhile grate the cheese. Fold the cheese into the vegetables and spread evenly on the polenta mass. Bake in the preheated oven (electric cooker: 200 °C/ gas: level 3) for 20-25 minutes. Serve garnished with mint to taste.