Make-Ahead Slow Cooker Beef Stew

INGREDIENTS

• 1/3 cup all-purpose flour
• 1 teaspoon Spanish smoked paprika
• 1/2 teaspoon seasoned salt
• 1/2 teaspoon ground black pepper
• 2 pounds beef chuck, cut into 1-inch cubes
• 1 tablespoon olive oil
• 1 onion, chopped
• 1 (8 ounce) package mushrooms, chopped
• 3 potatoes, diced
• 5 carrots, sliced
• 2 stalks celery, chopped
• 2 cloves garlic, minced
• 1/4 cup Marsala wine
• 1 tablespoon Worcestershire sauce
• 3 (10.5 ounce) cans organic beef broth
• 1 (14.5 ounce) can crushed tomatoes
• 1 (1 ounce) package dry onion soup mix
• 1 teaspoon Spanish smoked paprika, or to taste
• salt and ground black pepper to taste
• 2 tablespoons cornstarch (optional)
• 2 tablespoons water (optional)