Heat the oil and butter in a large frying pan over medium-high heat. Cook the mushrooms for 5 minutes or until golden and cooked, tossing regularly. Season with salt and pepper and squeeze over lemon juice to taste, tossing to combine

Meanwhile, heat a chargrill pan over medium-high heat. Drizzle the bread with oil. Toast the bread for 1-2 minutes each side or until charred. Serve the mushrooms on the sourdough with wilted greens and feta