season the beef with salt and pepper then brown in a large frying pan. Remove the meat and put in your slow cooker.
Add the onions to the pan and saute for a minute, then add the garlic and continue to saute til onions soften. Make sure to scrape up any brown bits from the meat. Add it all to the slowcooker.
Add the remaining beef ingredients to the slow cooker. Stir to combine and cook on low for 6-7 hours.
Transfer everything to a large high sided pan and simmer for another 10-15 minutes to reduce the liquid by half and adjust seasoning as necessary. Stir occasionally, but carefully, the meat is delicate and will fall apart, you want it to stay together in the burrito so it comes apart in your mouth.
Steam each tortilla for about a minute before using.
Grease a large skillet with a bit of olive oil and heat on medium til oil is almost smoking.
Make and roll the burritos! Watch this quick vid for the proper rolling technique so the ends close properly https://www.youtube.com/watch?v=h2-Hcd1LfWY
Place each burrito into the skillet and press down lightly so it changes shape from a ball to a rounded rectangle. Press in the pan for about 30 seconds, the flip and repeat.