Vegetarian sausage rolls

Name: Vegetarian sausage rolls
Ingredients: 2 tablespoon olive oil; 30 gram butter; 1 finely chopped onion; 1 finely chopped carrot; 1 peeled, finely chopped parsnip; 400 gram peeled, cubed kumara; 400 gram can, rinsed, drained lentils; 1 teaspoon curry powder; 1 cup tasty cheese, grated; 1/4 cup tomato relish, plus extra to serve; 3 sheets puff pastry, halved; 2 tablespoons milk, for brushing; 2 tablespoon sesame seeds; salad leaves, to serve