Wash, clean and cut vegetables. Peel, quarter and slice the onion. Peel and chop the garlic.
Put mixed vegetables, onions and garlic into the Römertopf, seasoning with salt, pepper and sugar every now and then. Place sprigs of thyme between the vegetables. Pour olive oil and broth over them.
Cover and cook in the oven at 230 ° for 30 minutes (be sure to put the Römertopf in the cold, not preheated oven!). Finally remove the thyme stalks and stir in the tomato paste.