Aromatic Lentil Tart

Name: Aromatic Lentil Tart
Ingredients: 1 square sheet of ready-rolled frozen puff pastry, thawed; 1 egg, lightly whisked; a cup (200 grams) of brown lentils, rinsed; 2 cups of vegetable stock or water; 2 garlic cloves, sliced; 2 medium-sized tomatoes, sliced; 2 tablespoon of olive oil; 6 pitted Kalamata olives, roughly chopped; a medium onion, finely diced; 5 fresh button mushrooms, sliced; 1 teaspoon of thyme; 1 medium-sized red bell pepper, roasted, peeled, deseeded and diced; 1 tablespoon of balsamic vinegar; 1 loose handful of grated Parmesan cheese; Salt and freshly ground black pepper to taste