In a heavy skillet heat bacon grease over medium heat, I just cooked up 5 slices of bacon first, then removed them from the pan, and added them to my burger bar, reserving the grease to cook my onions in.

Add in onions and mustard, stir well, then cover and turn down to low and let cook 1-2 hours, stirring occasionally, until caramelized and golden brown.

Grill burgers on exterior grill on medium-high heat, using a pan or foil, cook burgers in about 1/2 Tbs Heinz Yellow Mustard per patty for 3-4 minutes per side, until center reaches 160 degrees.

If using cheese, place cheese on burger, and move to top shelf in grill for 1-2 additional minutes to let cheese melt

Mix all ingredients together

Assemble burgers by putting mustard on bottom of brioche bun, then layering tomatoes, pickles, and lettuce, add burger patty, top with caramelized onions, and slather some special sauce on the top of the bun.

Enjoy