Clean, wash and slice the zucchini. Clean, wash and slice the peppers. Wash the rosemary and thyme and shake dry. Pluck the thyme leaves from the stalks.
Wash and halve the garlic. Wash potatoes thoroughly and cut in half. Put the Roman casserole dish in cold water for about 10 minutes. Wash the meat and dab dry. Mix vegetables, potatoes, 3/4 of the thyme, bay leaf and rosemary, season with salt and pepper.
Season the meat with salt and pepper as well. Remove the Roman casserole from the water. Add vegetable-potato mixture and garlic. Drizzle oil over it. Put the meat into it and cover it and put it in the cold oven.
Select the desired temperature (electric cooker: 175 °C/ circulating air: 150 °C/ gas: level 2) and cook for about 2 hours. Remove the lid 15 minutes before the end of the cooking time.