Stir and bring to the boil, then turn off the heat and transfer to a slow cooker. Cook on low for 8-9 hours or high for 6 hours (see tip below for cooking in the oven).
Once cooked, shred the meat using two forks.
Divide the meat between warmed tacos and top with red onion, fresh coriander, jalapenos, tomatoes, and sour cream.
Cooking in the oven instead of the slow cookerYou can cook the beef in a heavy-based, oven-proof pan, with a lid, in the oven at 160C for 3 hours. Add an extra 200ml of beef stock and check a few times during cooking to ensure beef doesn't cook dry. Add good splash of boiling water or stock if it starts to look too dry.Can I make it ahead?Yes, you can make the barbacoa beef ahead, then cool, cover and refrigerate for up to two days. Reheat in a large saucepan or frying pan over a medium heat, stirring often, until piping hot throughout. Then serve with the warm tacos and toppings.Can I freeze it?Yes, make the barbacoa beef ahead, then cool, cover and freeze. Defrost overnight in the refrigerator. Reheat in a large saucepan or frying pan over a medium heat, stirring often, until piping hot throughout. Then serve with the warm tacos and toppings.How to scale up and scale down this recipeYou can halve or double this recipe, sticking to the same recipe quantities. You may need an extra splash of stock if you're halving the recipe (to ensure it doesn't dry out).Nutritional information is approximate per taco including the toppings in the recipe (this recipe makes 12 soft tacos).