Depending on which cut of calamari you have, slice into bite size pieces, either rings or strips. If you have a whole squid, it is best to make a criss cross pattern on the outside of the meat and then cut it into bite size pieces. Dry the calamari using paper towels.
Using 1/2 cup of flour, toss the calamari until it’s completely coated. Dust off. In a separate bowl, mix the rest of the flour, cornflour, salt and ground pepper and add the soda water. Set aside. Heat up the oil in a frying pan. You need it hot enough so that when you add a drop of water it crackles. Dip each piece of calamari into the egg wash and then into the last flour mixture. Fry for 2-3 minutes. Drain on paper towels.
Add the garlic, salt and egg yolk to a food processor or bowl and mix (and electric beater works well). While continuing to mix, slowly drizzle the oil in. If you are doing this by hand and your mixture starts to split, stop adding the oil and whip until the mixture comes together again. Once all of the oil has been combined, stir in the lemon juice and mustard. Drizzle a little extra oil on top.
Serve your calamari with the aioli.