Heat half the oil in an 18cm (base) non-stick frying pan over medium-high heat. Add onion and mushroom. Cook, stirring, for 4 minutes until softened. Add garlic and thyme. Cook for 1 minute or until fragrant. Transfer mixture to a bowl. Wash and dry pan.
Using a vegetable peeler, peel potato into thin ribbons. Heat remaining oil in pan over medium-high heat. Arrange half the potato in pan.
Add eggs and peas to onion mixture. Season with salt and pepper. Stir to combine. Add egg mixture to pan. Reduce heat to low. Top with remaining potato, pushing slightly into egg mixture. Cook for 15 minutes or until just set.
Slide cake onto a plate. Cover plate with pan. Flip plate and pan over. Cook underside of cake for 15 minutes or until golden and potato tender. Cut into wedges. Serve with salad leaves.
