In a cup or bowl, add in the vinegar and chicken stock. Stir to combine and set aside.
Season the roast all over with salt and place in slow cooker.*
Throw in the jalapeños and garlic.
Pour the vinegar mixture over everything.
Cover and cook on low for 6-8 hours, until the beef comes apart easily using a fork.
Using two forks, shred the beef.
Keep warm until ready to devour.
Notes
Note 1: I use homemade chicken stock for this recipe, which doesn't have salt in it. If you are using store-bought stock, use half the amount of salt measured for this recipe.Note 2: Jalapeños can be tricky when it comes to heat. Sometimes, they are really hot and other times, they're on the milder side! If you want more heat, use more peppers. Alternately, you can play around with different peppers for various levels of heat and flavor.