For the Seaweed Mayo: Combine the mayonnaise, seaweed and lemon juice in a small bowl. Cover and refrigerate until ready to serve. (Makes 1/2 cup.)
For the squid: In a medium bowl, combine the squid, milk and half of the seasoning packet from the ramen; reserve the remainder of the packet for later use. Cover and refrigerate for at least 1 hour.
Drain the squid when ready to start cooking. Pour oil to a depth of 2 inches into a large heavy pot or Dutch oven. Heat over medium-high heat until the oil reaches 375 degrees F on a candy thermometer.
Meanwhile, break the block of noodles into chunks and pulse to small (1/4-inch) pieces in a food processor. Spread about half of the crushed noodles on a large plate (see Cook's Note). Put the cornstarch in a wide shallow bowl. In another shallow bowl, beat the egg with a splash of water.
Working in small batches, dredge the drained squid in the cornstarch and then toss in the egg, letting the excess drip off. Gently press both sides of the squid into the crushed noodles. Transfer to a large plate.
Carefully slip the ramen-coated squid into the hot oil and fry, stirring occasionally, until golden, 1 1/2 to 2 minutes. Transfer to a wire rack set over a foil-lined baking sheet or to a paper-towel-lined plate to drain. Immediately sprinkle the fried squid lightly with some of the remaining seasoning packet.
Repeat in small batches with the remaining squid, adding more ramen to the plate as needed. Between batches, skim the oil of any bits of noodles and be sure to allow it to return to temperature.
Serve the fried squid with lemon wedges and seaweed mayo.
Do not put all of the crushed noodles onto the plate at once. They'll get wet and clump together, and won't stick to the squid. Add more noodles to the plate as needed.