Heat the olive oil in a large, deep frying pan or a medium pot. Add the onions, carrots, celery and a pinch of salt. Cook over medium-low heat, stirring occasionally, until the vegetables have softened and are starting to brown (15-20 minutes).
2 onions (white, brown or red), 2 medium carrots, 2 sticks celery, 2 tbsp olive oil
Remove the vegetables from the pan/pot to a plate or bowl and set aside.
Return the pot to the heat and add the mushrooms, cooking until they release their liquid and start to brown.
300 g chestnut mushrooms
At this point, add the onion/celery/carrot mixture back into the pot along with the lentils, rosemary, oregano, soy sauce, balsamic vinegar, marmite (or miso/vegemite) and tinned tomatoes.
150 g red lentils, 3 sprigs rosemary, 1 tsp dried oregano or mixed dried herbs, 1-2 tbsp soy sauce, 1 tbsp balsamic vinegar*, 1 tbsp marmite, miso or vegemite, 2 x 400g tin chopped tomatoes or plum tomatoes
Fill up one of the tomato tins with water and add to the pot/pan as well. Place the pan over a high heat and bring to a simmer. Turn the heat down to low, cover with a lid, and leave to cook for 20-30 minutes, stirring occasionally until the lentils have softened. If you notice the sauce is looking dry whilst it's cooking, add more water as needed.
Remove from the heat. Stir in the Maggi liquid seasoning (if using) and the drained green lentils and set aside. Taste and adjust seasoning by adding more soy sauce (or salt), if needed.
1 tsp Maggi liquid seasoning, 1 x 400g tin cooked green lentils*