Shredded beef tacos

Original recipe from gimme some oven!

1-2 Tbs olive oil
2 lbs beef (boneless chuck roast
1 tsp chili powder
1/2 tsp cumin
1/2 tsp smoked paprika
1 cup beef stock
2 Tbs tomato paste
1/2 tsp chipotle pepper
1/2 large sweet onion, diced
4 cloves garlic, minced (smashed!)

Mix the chili powder, cumin, and paprika in a small dish and cover both sides of the meat with the spice mixture. Heat 1-2 Tbs olive oil in a pan, and sear the meat on both sides. Place the meat in the bottom of a slow cooker. Deglaze the pan with the beef stock, and whisk in the tomato paste and chipotle pepper. Bring the liquid to a boil for a few minutes, until reduced, then add to the slow cooker. Add the onion and garlic to the slow cooker as well. Cook on low for 6-8 hours. After cooking, pull the meat out of the slow cooker and shred. Strain out the onions with a slotted spoon and mix into the shredded meat.