Preheat the oven at 190°C or 375°F.
Wash and chop, dice and cut all the vegetables and the meat. Set aside on a chopping board or a plate grouped.
Place the pot on medium fire, add the meat chunks, the chopped onion, leek, chopped celery sticks, bay leaves, sliced carrots, cut into larger pieces flat beans and the potato chunks, celeriac, thyme and the crushed and chopped garlic. Cook for 2-3 minutes tossing from time to time. Add some salt too.
Add the water or stock add some salt and increase the heat to high.
Add all the remaining ingredients, the mixed lentils, tomato paste, chopped tomatoes, turmeric powder, paprika and spices. Mix well and transfer into the oven. Do not cover but make sure your dish is not too full as it will make a real mess in the oven.
Cook for 45-50 minutes until the liquid has reduced quite a bit.
When ready, take out carefully using oven gloves. Serve while hot and optionally sprinkle some chillies over and fully savour it. You can serve this on rice too if you like.