Clean and trim the mushrooms, halving the larger ones and keeping some whole.
Combine the mushrooms, onion and sliced fennel bulb in a bowl and drizzle with olive oil.
In a small blender, add the lemon juice, chilli, garlic, ginger and salt and blitz briefly. to chop and combine.
Pour the lemon mixture over the mushrooms and stir throughly to coat.
Leave to marinate for thirty to forty minutes, stirring occasionally.
Before serving, stir through the cubed avocado and the green fennel fronds.
Serve with sweet potato or alone.