Start by preparing your Brussels sprouts.
Remove the outer leaves and a bit of the bottom/root.
Rinse them under cold water and dry them with a clean tea towel.
Cut them in half (unless they are very large - then quarter them).
Heat a pan on relatively high heat (11 out of 14 on my stove) and add butter when it is hot. When it foams, add the sprouts.
Preferably place them with the cut side down so they can get the most sear where they are flat.
Fry them for a couple of minutes and turn them around.
Add lemon juice (and possibly parmesan) and let them cook for another 2-3 minutes.
Season with salt and pepper and add herbs if desired.