Halve lemon and into a bowl of cold water squeeze juice from 1 half, dropping squeezed half into water.
Do not cut off stems of artichokes. Working with 1 artichoke at a time, bend back outer leaves until they snap off close to base and discard several more layers of leaves in same manner until exposed leaves are pale green at top and pale yellow at base.
With a sharp stainless-steel knife cut off tops of leaves about 1 to 1 1/4 inches from top of artichoke. Trim fibrous parts from base of artichoke, being careful not to break off stem.
Cut a thin slice from end of stem to expose a fresh cross section. Trim outer green fibrous part from stem, leaving pale core intact. Rub artichoke all over with cut side of remaining lemon half and put artichoke in bowl of lemon water.
