Heat canola oil in a large nonstick skillet over medium-high heat. Add onion, sugar, vinegar, salt, and pepper; sauté 8 minutes or until golden. Remove onion mixture from pan. Add Canadian bacon to pan; cook 1 minute on each side or until lightly browned. Remove Canadian bacon from pan.
Wipe pan clean with paper towels. Coat pan with cooking spray. Reduce heat to medium. Add eggs to pan; cook 2 minutes on each side or until desired degree of doneness. Layer 1 Canadian bacon slice, 1/4 cup onion mixture, and 1 egg on each of 4 bread slices. Top with remaining bread slices.