Tempura

1. Before You Start: Gather all the ingredients. I encourage you to weigh your flour in metric using a kitchen scale. Click on the “Metric“ button at the top of the recipe to convert the ingredient measurements to metric. If you‘re using a cup measurement, please follow the “fluff and sprinkle“ method: Fluff your flour with a spoon, sprinkle the flour into your measuring cup, and level it off. Otherwise, you may scoop more flour than you need. 

To Make the Dipping Sauce (Tentsuyu)

1. Combine ¾ cup dashi (Japanese soup stock), 3 Tbsp soy sauce, 2 Tbsp mirin, and 2 tsp sugar in a small saucepan and bring it to a boil. Then, lower the heat and let it simmer until the sugar is completely dissolved. Remove from the heat and set aside. Tip: For a quick dashi, use ¾ cup (180 ml) water + 1 tsp dashi powder.

To Prepare the Ingredients

1. Peel 4 shrimp, leaving on the tail and last shell segment (closest to the tail). Straighten the shrimp so it looks gorgeous; learn how in my post on how to prepare shrimp. Pat dry to completely remove the moisture.
2. Cut 2 king oyster mushrooms (eringi), 4 slices lotus root (renkon), 4 slices Japanese sweet potato (Satsumaimo), and 4 slices kabocha squash each about ¼ inch (6 mm) thick. For the 1 Japanese or Chinese eggplant, cut off and discard the stem and calyx, then cut in half lengthwise. Place the halves flat side down on the cutting board and cut lengthwise into very thin slices (⅛ inch or 3 mm), leaving 1 inch (2.5 cm) of the bottom tip intact so the slices stay connected. Then, gently press down to fan out the slices. Keep the 2 shiso leaves (perilla/ooba) whole.

To Prepare the Oil

1. In a medium-sized pot, heat 1½–2 inches (3–5 cm) of neutral oil to 350°F (180°C). Tip: For enhanced aroma and taste, I like to add 1 part sesame oil for every 10 parts neutral oil.

To Make the Batter

1. While the oil is heating up, prepare the tempura batter. We‘ll use a 1-to-1 ratio (by volume) of flour to egg + water. First, add 1 large egg (50 g each w/o shell) and 200 ml iced water into a measuring cup or a bowl. Whisk the egg mixture vigorously. Discard the foam on the surface.
2. Next, sift 1 cup all-purpose flour (plain flour) into a large bowl. Slowly pour the egg mixture into the flour and mix. Do not overmix; it’s okay to leave some lumps. Keep the batter cold at all times. I store mine in the refrigerator until ready to use. Make the batter right before deep-frying to avoid activating the wheat gluten.

To Deep-Fry the Tempura

1. To get crispy tempura, make sure your ingredients are dry; pat them dry with a paper towel, if needed. Any excess moisture will make the tempura soggy. Next, arrange them in cooking order, starting with the cleaner and less astringent ingredients. I suggest cooking the shiso first, followed by the mushrooms, lotus root, eggplant, shrimp, sweet potatoes, and kabocha, in that order. 
2. Check that the oil temperature is 350°F (180°C) using a thermometer. To check with wooden chopsticks, dip them in the oil; when small bubbles form around the tips, the oil is ready. Tip: When you deep-fry, do not crowd the pot because the oil temperature will drop quickly. Your ingredients should take up no more than about half of the oil surface area at any one time. For more helpful hints, read my post How to Deep-Fry Food.
3. With the oil at 350°F (180°C), dip one piece of vegetable or shrimp (but not the potato or kabocha yet) in the batter, let the excess drip off for 1–2 seconds, and gently place in the hot oil. Continue to dip and add one piece at a time without crowding the pot. For the shiso leaves, sift 2 Tbsp all-purpose flour (plain flour), sprinkle a bit on the back of the leaf, and dip only the back into the batter. The flour acts as a glue that helps the batter adhere. For the shrimp, dust lightly with the flour (or potato starch/cornstarch) before dipping. Fry the shiso leaves for 15–30 seconds, mushrooms for 1 minute, lotus root for 2 minutes each side, eggplant for 1 minute, and shrimp for 2 minutes. (We‘ll cook the sweet potatoes and kabocha in the next step.) Deep-fry until golden brown.
4. Now, lower the oil temperature to 320ºF (160℃). Then, dip the sweet potatoes in the batter and cook for 3 minutes. Finally, dip and fry the kabocha for 2–3 minutes.
5. As the tempura cook to a golden brown, transfer them to a wire rack or a plate lined with paper towels to drain the excess oil. Repeat with the next batches.
6. In between batches, clean the oil by scooping up the crumbs (called tenkasu), which will burn and turn the oil darker if left in the pot.

To Serve

1. Peel and grate 2 inches daikon radish (I use a ceramic grater) and gently squeeze out some of the liquid. Prepare 3–4 Tbsp of warm tentsuyu in each individual dipping bowl with 1 Tbsp grated daikon per serving on the side.
2. Add the grated daikon to the dipping sauce, then dip the Tempura in the sauce to enjoy.

To Store

1. If you have unused dipping sauce, you can store it in the refrigerator for up to 1–2 weeks.You can keep the leftovers in a single layer between paper towels and put in an airtight container or a resealable plastic bag. Store in the freezer for 2 weeks. To reheat, place the tempura on a wire rack in the preheated oven (400ºF or 200ºC) or the toaster oven for 5 minutes or until crisp on the outside and heated through on the inside.