Put a large pan of water on to boil for the brussels.
Trim and halve brussels sprouts, drop into a pot of boiling water and cook for 3 minutes.
Drain, cool under cold water and drain again.
Heat butter in a large frypan and cook bacon over medium heat until fat starts to run (about 5 minutes). Add shallots or onion and cook for about 4 minutes.
Add brussels sprouts and stir-fry over high heat until tender and starting to caramelise (about 5 minutes).
Season with salt and pepper, drizzle with lemon juice, sprinkle with parsley and serve hot.
VARIATIONS: Try using broccoli if you can’t get brussels sprouts.