Slice clean, dry squid into 1/8-inch rings. If using medium-size squid, cut open squid and make a light crisscross pattern on the outside with a paring knife, then cut into approximately 1-inch pieces.
Heat oil in wok over medium heat to about 375 degrees. Mix salt, pepper, and cornstarch in a plastic bag. Add the squid, seal the bag, and shake it to coat each piece evenly. Put a few squid pieces at a time the palm of your hand and shake off the excess cornstarch mix. Working in batches, deep-fry the squid until the rings turn golden and crisp, about 1 minute, or if using 1-inch square pieces, until they curl up and crisp, about 1 minute. Drain on paper towels and serve with lime wedges on the side.