• 2 lemons, halved
• 4 large artichokes
• 6 cups olive oil or vegetable oil

• Special equipment: a deep-fat thermometer

 
Fill a large bowl with cold water and squeeze juice from 2 lemon halves into bowl.
Keep stem attached and, at opposite end, cut off top inch of 1 artichoke with a serrated knife. Bend back outer leaves until they snap off close to base, then discard several more layers of leaves in same manner until you reach pale yellow leaves with pale green tips. Trim dark green fibrous parts from base and side of artichoke with a paring knife, then rub cut surfaces with a remaining lemon half.
Trim 1/4 inch from end of stem to expose inner core. Trim sides of stem (still attached) down to pale inner core (don't worry if remaining stem is very thin). Cut off pale green top of artichoke, then cut artichoke lengthwise into 6 wedges. Cut out purple leaves and fuzzy choke. Rub cut surfaces with remaining lemon half and put in bowl of acidulated water. Trim remaining artichokes in same manner.
Drain artichokes well on paper towels and pat dry. Heat oil in a 4-quart deep heavy saucepan over moderate heat until thermometer registers 220°F, then simmer artichokes in oil, gently stirring occasionally, until tender, about 15 minutes. Transfer with a slotted spoon to paper towels to drain.
Continue to heat oil over moderate heat until thermometer registers 375°F, then fry artichokes in 4 batches until leaves are curled, browned, and crisp, 30 to 40 seconds. (Return oil to 375°F between batches.) Drain well on paper towels and season with salt.
Adapted from epicurious.com