Using a sharp knife, mince the frozen bacon (a food processor would overprocess it). Mix all the patty ingredients, and then gently form six patties of equal size, each about 18 millimeters thick. With your thumb or the back of a spoon, make a shallow indentation about 2.5 centimeters wide in the center of each patty to prevent them from forming a dome as they cook. Refrigerate the patties until ready to grill.
Prepare the grill for direct cooking over medium-high heat (200° to 230°C).
Lightly brush the patties with oil, and then grill over direct medium-high heat, with the lid closed, until cooked to medium doneness (70°C), 8 to 10 minutes, turning once. During the last 30 seconds to 1 minute of grilling time, top each patty with a slice of cheese to melt, and toast the buns, cut side down, over direct heat.
Lightly brush the patties with oil, and then grill over medium-high heat, with the lid closed, until cooked to medium doneness (70°C), 8 to 10 minutes, turning once. During the last 30 seconds to 1 minute of grilling time, top each patty with a slice of cheese to melt, and toast the buns, cut side down, over direct heat.
Spread the bottom bun halves with mayonnaise and the top halves with mustard. Build each burger with a lettuce leaf, two tomato slices, a patty, three pickle chips, and an onion slice. Serve warm.
