Spicy Beef Vegetable Stew

1 pound ground beef

1 cup chopped onion

1 (30 ounce) jar meatless spaghetti sauce

3 ½ cups water

1 (16 ounce) package frozen mixed vegetables

1 (10 ounce) can diced tomatoes with green chile peppers

1 cup sliced celery

1 teaspoon beef bouillon granules

1 teaspoon ground black pepper

Heat a large skillet over medium-high heat and stir in ground beef and onions. Cook and stir until beef is crumbly, evenly browned, and no longer pink, about 10 minutes. Drain and discard any excess grease.

Transfer beef mixture to a slow cooker. Stir in spaghetti sauce, water, mixed vegetables, diced tomatoes, celery, beef bouillon, and pepper. Cover and cook on Low until vegetables are tender, about 8 hours.