Form the meat into eight equal-sized balls (1/4 lb each).

Flatten each ball of meat between wax paper to about 1/4" thick and about 5" in diameter.

Stack the wrapped burgers in a gallon zip-top bag and freeze until you're ready to grill.

Heat a large heavy pan over medium-high heat, then add the oil.

Add the onions, and half of the salt and pepper, then saute until the onions are translucent and just starting to brown, about 15 minutes.

While the onions are cooking, start your grill and prepare for direct grilling at medium-high heat (350-375º).

Add the Worcestershire to the pan, stir well, and cook another minute.

Cover the pan, remove from the heat and set aside.

Season one side of the burgers with the remaining salt and pepper.

Grill each burger for about two minutes per side then top each with a slice of cheese, 1/4 cup of onions, another slice of cheese, and another 1/4 cup of onions.

Move the burgers to one side of the grill and quickly toast the buns on the other side.

Gently slide each burger onto a bun and serve with your side of choice. I served mine with slabs of grilled zucchini."