Start with your beef brisket. Season it generously with salt and pepper, or any other spices you prefer to enhance the flavor.
Place the seasoned brisket in your slow cooker. Optionally add beef broth or marinade to keep it moist during cooking.
Set your slow cooker to low and cook the brisket for about 8 hours, or until fork-tender. Alternatively, cook on high for 4-5 hours if short on time.
Once cooked, remove the brisket from the slow cooker and let it rest for a few minutes. Then shred the meat into bite-sized pieces using two forks.
Warm your flour tortillas in a skillet or over a flame until soft and pliable.
Assemble the tacos by adding a generous portion of shredded brisket to each tortilla. Top with diced red onion, fresh cilantro, sliced jalapeno, and crumbled cotija cheese.
Serve the tacos immediately while warm, with your favorite salsa or hot sauce on the side.