Prepare the Ingredients:

• Wash and cut the vegetables (zucchini, sweet potato, bell pepper, mushrooms) into bite-sized pieces.
• If using shrimp, ensure they are peeled, deveined, and tails are removed.

Make the Dipping Sauce:

• In a small saucepan, combine soy sauce, dashi stock, and mirin. Heat gently and stir until mixed. Set aside.

Prepare the Batter:

• In a mixing bowl, whisk together the egg and cold water.
• Add the flour and baking soda, and mix gently. It’s okay if the batter is a little lumpy—overmixing can lead to a heavy texture. Let the batter rest for about 10 minutes.

Heat the Oil:

• In a deep skillet or pot, heat about 2 inches of vegetable oil over medium-high heat (around 350°F or 175°C). To test if it’s ready, drop a small amount of batter into the oil; it should sizzle and rise to the surface.

Fry the Tempura:

• Dip the vegetables and shrimp into the batter, allowing excess batter to drip off.
• Carefully place them in the hot oil, frying in batches to avoid overcrowding.
• Fry until golden brown and crispy, about 2-3 minutes for vegetables and 1-2 minutes for shrimp.
• Use a slotted spoon to remove tempura and place it on a paper towel-lined plate to drain excess oil.

Serve:

• Arrange the tempura on a serving platter and serve hot with the dipping sauce and grated daikon on the side.