Trim the ends and remove any loose leaves from the Brussels sprouts. Make a small slit across the base of the stem. Put the sprouts in a large steamer and cover with a lid. Sit the steamer over a saucepan of boiling water and steam for 15 minutes, or until tender. Refresh under cold water to stop the cooking process.

Put the butter, mustard, and honey in a saucepan over low heat and stir to melt the butter. Add the sprouts and toss until well coated in the butter mixture and heated through. Pile onto a plate and serve immediately.