Delicious Shredded Beef Tacos

I haven't been posting any of our new favorite recipes because I have been lazy about taking pictures, but then when I want to make them again I am frustrated that I have to search and find I'm just borrowing other people's pictures and getting some posted!
(picture from Jennifer Cooks)
First up is this delicious new recipe I found for shredded beef. I adjusted things a bit from one I found on and I really loved! Flavorful and juicy and absolutely heavenly when served in freshly fried corn tortilla shells!

1 large yellow onion, sliced into thin rings
1 (2 pound) boneless beef chuck roast, trimmed
1 (14.5 ounce) can fire roasted tomato salsa
1/2 cup beef broth
1 (4 ounce) can diced green chiles
2 jalapeno peppers, sliced (optional)
4 cloves garlic, chopped
1 teaspoon chili powder
1 teaspoon ground cumin
1/2 teaspoon salt
1/4 teaspoon ground black pepper

Layer half the onion rings into the bottom of a slow cooker. Place chuck roast on top of onions.
Pour diced tomatoes, beef broth, and coffee into the cooker over the roast; stir in diced green chiles, jalapeno peppers, garlic, chili powder, cumin, salt, and black pepper. 
Spread remaining onion rings over the mixture.
Cover the cooker and cook on Low until beef is very tender, 6 to 10 hours.
Transfer chuck roast to a bowl and shred meat. Return meat to sauce. 
Remove onions and serve with meat.