Fry the onion, celery and carrot with the cumin and coriander in the olive oil until lightly browned. Add the tin of tomatoes and the tomato puree. Add the lentils. Add the stock, cover and simmer for about 45 minutes. Season with salt and pepper.
For the roasted veg: Preheat the oven to 200 C / Gas 6.
Quarter the tomatoes. Cut the peppers into thick strips. Finely chop the garlic and place all the said ingredients into a bowl. Add the balsamic vinegar, fennel seed, salt, pepper and sugar, then drizzle the olive oil. Coat well, place onto a baking tray.
Roast in the preheated oven until softened and slightly charred.
Once the lentils are cooked right through, place into a serving bowl and spread the roasted veg on.