1. Divide the meat into 4 equal portions (about 6 ounces each). Form each portion loosely into a 3/4-inch-thick burger and make a deep depression in the center with your thumb.
Season both sides of each burger with salt and pepper.
2. Heat a gas grill to high. Brush the burgers with canola oil and grill until desired doneness is reached. Top each with 2 slices of cheese and cover during the last minute of cooking.
3. Place the burgers on the bun bottoms and, if desired, top with tomato, lettuce, onion, and dollop of horseradish mustard mayonnaise. Pile on the potato chips, cover with the bun tops, and serve immediately.