Method
Lightly spray a large non-stick frying pan with oil and set over a low to medium heat. Add the mushrooms and cook for about 5 minutes, turning once or twice, until tender and golden brown. Remove and keep warm.
Cut the tomatoes in half horizontally and add to the pan. Cook for 3–4 minutes, turning once, until tender and starting to brown. Alternatively, cook the mushrooms and tomatoes under a hot overhead grill.
Meanwhile, bring a small saucepan of water to the boil, then reduce the heat to a bare simmer and gently break the eggs into the hot water. Cover the pan and cook gently over the lowest possible heat for about 3–4 minutes until the whites are set but the yolks are still runny. Remove with a slotted spoon and drain on kitchen paper.
While the eggs are poaching, lightly toast the bread. Spread the tomato ketchup over each slice of toast and place a few lettuce leaves on top. Add the tomatoes and mushrooms and top each one with a poached egg. Grind over some salt and pepper and serve immediately.