In a bowl, combine first 4 ingredients. Let stand 5 minutes.
Preheat large Fry Pan or grill pan over medium heat. Add oil. Using a 1-C (250-ml) measure as a guide, scoop batter into pan, making 4 burgers. Lightly press and flatten into shape. Cook until golden brown, about 4–5 minutes per side.
Divide half the lettuce leaves on plates; dollop with Big Burger Sauce. Cover with patties and toppings, then remaining lettuce.
Recipe Tip: Make burgers; refrigerate or freeze. Reheat on barbecue for smoky flavour.