2-1/2 pound well-trimmed top round roast or flat half brisket
1/2 teaspoon coarsely ground black pepper
2 cups sliced fresh mushrooms
1 cup chopped onions
1 cup chopped red or green bell peppers or 1 cup roasted bell peppers, drained and chopped
14-1/2 ounce can diced Italian-style tomatoes, undrained
6-ounce can tomato paste with roasted garlic or Italian seasonings
Rinse the meat with cool water and pat it dry with paper towels. Sprinkle both sides with some of the pepper.
Coat a large nonstick skillet with nonstick cooking spray and preheat over medium-high heat.
Place the meat in the skillet and cook for 2 to 3 minutes on each side, until nicely browned.
Place the mushrooms, onions, and bell peppers in a 3-quart slow cooker and top with the roast. Pour the tomatoes over the meat. Cover and cook on high for 5 hours or on low for 10 hours, until the meat is very tender.
Remove the roast to a serving platter and cover loosely with aluminum foil to keep warm. Add the tomato paste to the remaining slow cooker mixture and stir to mix well.
Slice the roast across the grain and serve hot accompanied by the sauce. Serve with pasta if desired.