Thinly slice the onion, garlic, pepper and roughly chop the tomatoes.
Heat some oil in a large frying pan and gently sauté the pepper, onion and garlic ( under a lid). When they are tender ( not soft) add the tomatoes and cook for another 5-8 minutes until the tomatoes have softened. Add the paprika, and stir for 30 seconds.
Drain the lentils and add to the pan together with the lemon juice. Season generously with ground pepper and some salt to your taste. Warm through, then fold in the chopped parsley.
Taste and adjust the seasoning (see tip).