Who can resist delicious crispy homemade vegetable tempura? When making tempura at home, the goal is a crispy yet airy coating that doesn't absorb oil when deep fried. I’ll teach you how to achieve excellent results in this recipe.
Combine dashi stock, mirin, sugar, and soy sauce in a small saucepan and bring it to a boil. Then lower the heat and let it simmer until sugar is completely dissolved. Remove from heat and set aside.
To Prepare Tempura Ingredients
Gather all the ingredients.
Slice Japanese sweet potato into thin pieces and soak in water for 15-30 minutes to remove excess starch. Then dry them using paper towels.
Cut kabocha squash and lotus root into thin slices. Soak lotus root in vinegar water (2 cups water + 1 tsp vinegar).
Cut King oyster mushroom into thin slices.
Discard the head of the eggplant first, then cut it in half lengthwise. Then cut the eggplant lengthwise into very thin (⅛ inch, 3 mm) slices leaving the top 1-inch part intact. Gently press down on the eggplants to fan the slices out.
Once the ingredients are ready, heat 1 ½" (3 cm) of the oil to 356ºF (180ºC) in a deep-fryer or pot. To make the batter, sift the flour into a large bowl.
To Make Tempura Batter
Gather all the ingredients.
Sift all-purpose flour.
Add the egg into very cold water.
Whisk vigorously and discard the form on the surface.
As you slowly pour the egg mixture into the flour, mix the batter for about 1 minute with chopsticks in a figure 8 motion. Do not over mix and leave some lumps in the batter to avoid activation of wheat gluten. Keep the batter cold all the time by adding 1-2 ice cubes in the batter or by putting the batter bowl in a larger bowl containing ice water.
Start deep-frying from the root vegetables as oil temperature needs to be a bit lower than non-root vegetables. If the ingredient is wet, dry them with a paper towel before dredging in the batter. While tempura is being fried, moisture from the ingredients will be evaporated and tempura will become crispy. However, if the ingredients have extra moisture, the tempura will become soggy after being deep-fried.
For root vegetables, deep-fry at 320°F (160°C) for 3-4 minutes. For vegetables and mushrooms, at 338-356°F (170-180°C) for 1-2 minutes. Do not overcrowd with ingredients. Remember you only put ingredients taking up about half of the oil surface area. When you put too many ingredients, the oil temperature will drop quickly. Make sure to keep the right temperature all the time. For shiso leaves, sprinkle a bit of sifted flour on the back of the leaves and dip only the back of the leaf into the batter, and deep-fry for 15 seconds. For ingredients that are hard to keep the batter on, such as Shrimp Tempura, Kakiage, or shiso, we dust extra flour before dredging the ingredient in the batter. Flour works as glue and the batter tends to stay on the ingredients.
Transfer tempura to a wired rack or paper towel to remove excess oil.
Between batches, using a fine-mesh strainer, remove the tempura crumbs, which will burn and turn the oil darker if you leave them in the oil.
Grate daikon and squeeze water out. Serve tempura immediately with grated daikon. To enjoy, add grated daikon in the tempura dipping sauce for a refreshing taste.
You can keep the leftovers in an airtight container and store in the refrigerator for 2 days or in the freezer for a month. To reheat, use the oven or oven toaster to make the tempura crispy again.