4 lb chuck roast
1 tsp ground cumin
1 tsp mild chili powder
1/2 tsp kosher salt
1/2 tsp fresh black pepper
1 medium onion, peeled and quartered
1 14-oz can Ro*Tel (or diced tomatoes with green chiles)
4-oz can diced green chiles
Trim the roast to remove the largest pieces of fat. You'll end up with several big chunks of meat, a total of 3-1/2 pounds or so. Place the meat in a large mixing bowl.
In a small bowl, combine the cumin, chili powder, salt and pepper. Rub this mixture on all sides of the meat.
Heat a large, deep, nonstick frying pan. Over medium heat, brown the pieces of beef on all sides (in batches, if necessary).
Place the onion in the base of a 4-quart slow cooker. Top with the browned beef. Pour the can of Ro*Tel into the frying pan, and with a rubber spatula, scrape up the brown bits from the pan (using the liquid from the Ro*Tel to deglaze the pan). Pour the Ro*Tel into the slow cooker, along with the can of green chiles.
Cook on LOW for 7 hours. The meat will be falling-apart tender. Remove it to a casserole or deep-sided platter, along with enough of the cooking liquid to almost cover. Serve hot, over noodles or shredded in a taco or burrito, or allow to cool completely and refrigerate or freeze.