Lentil ragu

Name: Lentil ragu
Cuisine: European, Italian, Mediterranean
Ingredients: 450g Olive Green Lentils; 1 large Red Onion; 1 stick Celery; 1 Red Pepper; 3 cloves Garlic; 2 cans Tomatoes (or a large jar of Passata); 1 tbsp Tomatoe Puree (or finely chopped Sundried Tomatoes); 2 Bay Leaves; 1 sprig Rosemary; 1 bunch Fresh Parsley; 1 generous pinch dried Oregano; Vegetable Stock to cover; Salt & Pepper to taste