1 tablespoon vegetable oil 1 small brown onion, diced 2 cloves garlic, minced 500 g beef mince (ground beef) (1.1lb) ¼ cup taco seasoning 2 tablespoons tomato paste 2 ½ cups beef stock (beef broth) (625ml) 1 cup taco sauce (250ml) ¾ cup tinned black beans 2 large roasted peppers, diced (1 cup chopped/210g) 250 g large dry pasta shells (about 1 inch long) (3 cups/8.8oz) ½ teaspoon fine sea salt ½ cup sour cream (light or full fat) 1 ½ cups not packed, shredded cheddar cheese (180g/6.3oz)