Step 1 Place mayonnaise in small microwave-safe bowl; whisk in milk. Microwave on Medium (50% power) just until hot, about 45 seconds, stirring after 30 seconds. Whisk in Parmesan cheese, lemon juice and rind until smooth. Set sauce aside.
Step 2 Spray large non-stick skillet with cooking spray. Heat skillet over medium heat. Crack eggs into skillet. Break yolks with edge of spatula. Cook eggs to preferred doneness.
Step 3 Place tomato slices on 2 slices of bread. Top with fried egg. Spoon about 1 tbsp (15 mL) warm sauce over each egg. Cover with second slice of bread.