Loose Meat Crockpot Sandwiches

In a crockpot place:
1 lb. ground beef
1 lb. ground turkey
1 onion finely diced
2 tsp. sea salt
2 T sugar
2 T yellow mustard
2 T apple cide vinegar
4 C beef broth
Mix well. Cover and cook on low for 8-10 hours. Stir well before serving. Scoop onto hamburger buns and serve with desired toppings ( pickles, lettuce, tomatoes, mustard)