On grill or grill pan, sear roast on all sides, about 4 minutes per side over medium high heat. Move to plate and let rest/cool for 10-15 minutes.

Combine minced chiles, adobo sauce, oil, syrup, cumin, salt, and pepper in small bowl.

Put onions in bottom of slow cooker and pour in beef bone broth.

Rub adobo mixture over roast, and put roast in slow cooker over the onions. Pour any remaining adobo mixture on top of roast.

Cook on low for 7 1/2 hours. Shred meat with two forks, stir, and enjoy! You can make this in advance and warm up on day of, and the spices become richer. We use this for tacos, paired with some cilantro and shredded cheddar jack cheese.