Put the oil in a frying pan over high heat. Bash the salt and peppercorns in a mortar and pestle until a bit more than bruised but not quite pulverized, and combine this mixture in a freezer bag with cornstarch, adding the squid and tossing to coat well but not heavily.
When the oil's very hot - not quite smoking, but nearly - fry the squid (knocking any excess cornstarch back in the bag first) in batches (about 4, probably) and cook each batch for about 1 minute or so until just crisp on the outside and still sweet and tender within. You probably won't need to turn the squid since the oil should bubble up and cook both sides at once, but do if you feel better. Remove to plates lined with a paper towel. After the squid's sat for about half a minute, remove the greasy towel - though sometimes, I dispense with this stage - squeeze lemon over and eat with your fingers, quickly.