Vegetarian casserole

Name: Vegetarian casserole
Ingredients: 1 tbsp olive or rapeseed oil; 1 onion, finely chopped; 3 garlic clove, sliced; 1 tsp smoked paprika; ½ tsp cumin; 1 tbsp dried thyme; 3 medium carrot, sliced (about 200g); 2 medium sticks celery, finely sliced (about 120g); 1 red pepper, chopped; 1 yellow pepper, chopped; 2 x 400g tins tomatoes or peeled cherry tomatoes; 250ml vegetable stock cube (we used 1 Knorr vegetable stock pot); 2 courgette, sliced thickly (about 300g); 2 sprigs fresh thyme; 250g cooked lentil (we used Merchant Gourmet ready-to-eat Puy lentils)