Cook the lentils according to the package instructions. Preheat the oven to 200°C (top/bottom heat). Line or grease a loaf tin (25 cm) with baking paper.

Wash and dry the vegetables. Divide carrots, leeks, mushrooms and celery into fine cubes. Peel the garlic and chop in to fine slithers. Heat olive oil in a large pan and fry the vegetables for 5-10 minutes. Add the garlic and strip off the thyme leaves and add them too. Mix everything together and season with salt and pepper.

Finely chop the pistachios in a food processor. Mix vegetables, pistachios, tomato paste, mustard, salt and pepper, soy sauce, oat flakes, flour and eggs in a bowl.

Pour the mixture into the baking pan and bake in the oven (center) for 40-50 minutes. Remove from the oven, let cool for 20 minutes and remove from the baking pan.

Cut into slices and serve with salad or potatoes and sauce.