Heat half the oil in a medium non-stick frying pan over high heat. Add all the mushrooms; cook, stirring occasionally, for 5 minutes or until golden brown and liquid has evaporated. Add vinegar; cook, stirring, for 2 minutes or until liquid is absorbed and mixture is dry. Remove pan from heat; stir in spinach. Drain away any excess liquid.

Heat remaining oil in a non-stick frying pan; cook eggs to your liking.

Place each piece of toast on a serving plate; top with mushroom mixture and a fried egg. Season with freshly ground black pepper.