Pour the chicken stock onto the bottom of the slow cooker insert.
Place the flank steak into the chicken broth. If it doesn’t fit whole then cut the steak in half and lay the pieces next to each other in the slow cooker. If you need to layer the pieces slightly that’s fine just don’t put the pieces on top of one another.
Sprinkle the taco seasoning over the steak and then pour the salsa on top.
Add the onions and peppers on top of the steak and salsa.
Cover and cook for 6 – 8 hours on low or 3-4 hours on high.
Using tongs remove the steak from the slow cooker and place it onto a serving plate. Let the steak rest for 5 minutes before slicing. With the same tongs or a slotted spoon, remove the vegetables and place them next to the steak.
Squirt the lime juice onto the steak and vegetables, then sprinkle with salt and pepper.
Serve hot with tortillas or over rice.