"Tastee" Sandwich

Ingredients (10)

• + 4 ounces ketchup, or more to taste add to pantry
• + 5 teaspoons salt add to pantry
• + 1 tablespoon prepared mustard add to pantry
• + 1 tablespoon creamed horseradish add to pantry
• + 1 tablespoon Worcestershire sauce add to pantry
• + ¼ teaspoon ground black pepper add to pantry
• ✓ 5 pounds 85% lean ground beef
• + 1 cup warm water add to pantry
• + 1 cup minced onion add to pantry
• + 1 teaspoon monosodium glutamate (such as Ac'cent®) add to pantry