Dry fry the mince in a frying pan until brown and crumbly, stirring occasionally and breaking it up with a wooden spoon.
Add the onion, capsicum and garlic; cook, stirring occasionally, until softened. Stir in the herbs and spices; season to taste with salt and pepper. Add the tomato puree and mix well. Cover and cook gently for 10 minutes, stirring occasionally.
Place a little of the mixture on each taco shell then layer the avocado, lettuce, tomatoes cheese and sour cream,