Spaghetti Sauce (the best)Ingredients675 g (1 ½ lb) sweet or spicy Italian sausage (ideally a mixture of both), casing removed675 g (1 ½ lb) lean ground beef60 ml (¼ cup) olive oil1 to 2.5 ml (¼ to ½ teaspoon) crushed red pepper flakes3 onions, finely chopped4 carrots, peeled and diced4 stalks celery, diced4 cloves garlic, f…