Start by cleaning the squid. Remove the ink sac, beak, and any tough cartilage. You can also peel off the outer skin if you prefer. Score the body of the squid lightly in a crosshatch pattern; this helps it cook evenly and prevents curling.
Wash the potatoes and cut them into bite-sized pieces. Boil them in lightly salted water for about 8-10 minutes, or until they are tender-crisp. Drain them well and let them cool slightly.
Wash the red pepper, zucchini, and mushrooms. Cut the red pepper and zucchini into thick slices or large chunks. Leave the mushrooms whole or halve them if they are very large.
Mince the garlic cloves finely. Wash the fresh green leaves and slice the carrots into thin ribbons or sticks for decoration. Slice one of the lemons into wedges for serving.