Crispy Assorted Seafood and Vegetable Tempura

Prepare the seafood and vegetables: Peel and devein the shrimp, leaving the tails on. Score the belly side of each shrimp 2-3 times to prevent curling. Slice the squid into rings. Slice the eggplant and sweet potato into 0.5 cm thick rounds. Trim the stems of the shiitake mushrooms. Pat all ingredients very dry with paper towels.

Make the tempura batter: In a large bowl, whisk together the egg yolk and ice-cold water. Add the all-purpose flour and cornstarch to the liquid. Mix briefly with chopsticks or a fork until just combined; it's okay if there are still some lumps, as overmixing will develop gluten and make the tempura less crispy. Keep the batter very cold.

Heat the oil: Pour the frying oil into a deep pot or wok to a depth of about 5 cm. Heat the oil over medium-high heat until it reaches 170-180°C. You can test the temperature by dropping a tiny bit of batter into the oil; it should sink slightly then float up with gentle bubbles.

Dip and fry: Lightly dredge each piece of seafood and vegetable in a thin layer of dry flour (from the measured amount), then dip into the cold tempura batter, ensuring a thin, even coating. Gently slide 3-4 pieces into the hot oil, ensuring not to overcrowd the pot.

Fry until golden: Fry for 2-3 minutes, flipping once, until the tempura is lightly golden and crisp. Use a spider or slotted spoon to remove the tempura from the oil and place it on a wire rack lined with paper towels to drain excess oil.

Serve immediately: Repeat with the remaining ingredients, maintaining the oil temperature. Serve the crispy tempura immediately with a sprinkle of sea salt or with traditional tempura dipping sauce (Tentsuyu).