If using frozen squid, defrost it overnight in the refrigerator and pat it dry thoroughly with paper towels. Cut the squid into thick rings, about half an inch thick.

In a medium bowl, combine flour, cornstarch, baking powder, salt, and black pepper. Whisk until well mixed.

Dredge the squid rings one at a time in the flour mixture, ensuring each piece is thoroughly coated and shaking off excess flour.

Heat oil in a heavy pot over medium-high until it reaches 350°F. Test with a small bit of the flour mixture; it should sizzle.

Carefully add the coated squid to the hot oil in batches, frying for 2–3 minutes until golden brown.

Remove squid with a slotted spoon and place on paper towels to absorb excess oil.

In a small bowl, mix mayonnaise and minced garlic until well combined.

Serve the fried squid with garlic mayo and lemon wedges.