Cut the squid into rings about ½cm thick. Tip the flour into a freezer bag and season well. Add the capers, then give everything a good shake to mix together. Tip the squid into the bag, then shake again until all the rings are well coated. Mix together the garlic and mayonnaise, then place in a serving bowl.
Pour some oil into a large pan until it comes about 7cm up the sides, but the pan is no more than a third full. Place over a medium heat and let the oil warm up. To test that the oil is ready, place a small piece of bread in the pan - it should sizzle when it touches the oil.
Remove a handful of squid from the flour and shake off any excess. Gently drop into the oil, then cook for about 3 mins until crisp. Remove with a slotted spoon and place on kitchen paper. Repeat with the remaining squid. Serve straight away with the mayonnaise and lemon wedges.