Brush the mushrooms on both sides with a little olive oil and season with a pinch of salt and pepper.
Place the low protein breadcrumbs, garlic, lemon zest and parsley in a bowl with a little salt and pepper. Add in the remaining olive oil and spoon the mixture into the mushrooms.
Grill the mushrooms for 6–7 minutes, or until just cooked through.
Meanwhile, make the lemon and rosemary dressing by mixing all of the ingredients together.
Drizzle each mushroom with the lemon dressing. Serve with a green salad.