lentil sauce

This is something my Mum always cooked when I was little, and tasting it makes me nostalgic. It's also really tasty, whether on top of pasta, topped with mashed potatoes and baked to make a vegan shepherd's pie, or add a bit of water to it and blend it to make soup. Quantities are not exact, this makes about 6 servings. The cumin seeds in this recipe are vital to it tasting right.

2 tins of tomatoes
1 medium onion, diced
3 cloves of garlic, finely sliced
4 or 5 stalks of celery, including the leaves, diced
3 medium carrots, diced
1 tbsp tomato paste
1 tbsp cooking sherry
200g dried red lentils
1 tsp cumin seeds
2 tsp soy sauce
olive oil for frying the vegetables
salt and pepper, if needed

-Heat the olive oil in a heavy bottomed pan and fry the onion until it is soft. Add the garlic, fry for another minute or so.
-Add the celery and carrots. Fry for a couple of minutes and then add the lentils, tinned tomatoes, tomato paste, cumin, soy sauce and sherry.
-Turn the heat down and simmer until the lentils are cooked through. This could take about 30 minutes. Check the sauce often and add some water if it looks like the sauce is getting too dry.
-Add salt and pepper if you want, then eat. This freezes really well, btw.