When zesting and juicing a lemon, always zest first. Use a zester or grater and make short, sweeping strokes, rotating the fruit slightly after every 1 or 2 swipes. Avoid removing the white pith, which imparts bitterness. To extract the most juice, press and roll the lemon on the countertop to crush it slightly, then halve it crosswise. For small amounts of juice, use a hand reamer or juicer, rotating the lemon and pressing and squeezing until all the juice is released. For large amounts, electric juicers are efficient, but use caution as they may oversqueeze and extract bitter pith.