2 large onions, sliced thin
2 Tbsp. salted butter
2 pounds lean ground beef
2 Tbsp. ketchup
2 Tbsp. mustard
2 tsp. garlic salt
10 slices Rye bread (If you don't have Rye, sourdough works well.)
10 slices Swiss cheese
1/4 cup coconut oil (Olive oil will also work.)
Melt butter in a large frying pan over medium high heat. Add sliced onions and sauté for 15 minutes, stirring often, until onions are golden brown. Remove from heat and set aside.
Preheat BBQ to medium. Combine ground beef, ketchup, mustard and salt in a large mixing bowl using bare hands to mix. Form meat into 5 large rectangular patties. Grill for 5-6 minutes per side until burgers are cooked through. Remove from grill.
While patties are grilling, brush one side of each slice of bread with coconut oil. To assemble Patty Melts, place one burger patty on a slice of bread, oil side facing out. Top patty with one slice of cheese and 3-4 Tbsp. grilled onions. Place another slice of bread on top of onions, oil side out. Return sandwiches to hot BBQ and grill for 2 minutes per side until cheese is melted. Serve immediately.