Zaru Soba with Tsuyu, Wasabi, and Tempura

Why You’ll Love This Recipe

• Refreshing balance: cool, springy soba with a savory-sweet, bracing tsuyu.
• Textural contrast: crisp, airy tempura alongside silky noodles.
• Flexible and seasonal: use the freshest vegetables you have.
• Make-ahead friendly: tsuyu improves after chilling, so dinner is easy.

Grocery List

• Produce: Scallions, seasonal vegetables (sweet potato, asparagus, shiitake, etc.), optional shiso leaves, optional daikon for grating.
• Dairy/Refrigerated: 1 large egg, wasabi paste (usually refrigerated after opening).
• Pantry: Dried soba noodles, nori, soy sauce, mirin, sugar, kombu, katsuobushi or instant dashi, cake or all-purpose flour, cornstarch, baking powder, kosher salt, neutral frying oil (canola/peanut), optional bottled mentsuyu.

Full Ingredients

Soba & Garnishes

• 12 oz (340 g) dried soba noodles
• 1 sheet nori, lightly toasted and cut into fine strips
• 4 scallions, thinly sliced (about 1/2 cup / 40 g)
• 2 tsp (10 g) wasabi paste, plus more to taste
• Ice cubes for chilling noodles (about 4 cups)

Tsuyu (Dipping Sauce)

Option A: Homemade Tsuyu

• Water: 3 cups (720 ml) for dashi
• Kombu: 1 piece, about 4 x 4 in (10 x 10 cm), ~10 g
• Katsuobushi (bonito flakes): 1 cup loosely packed (~15 g)
• Soy sauce: 1/2 cup (120 ml)
• Mirin: 1/2 cup (120 ml)
• Granulated sugar: 1 tsp (4 g)

Option B: Shortcut Tsuyu

• Instant dashi powder: 2 tsp (6 g) + water: 2 cups (480 ml), or
• Bottled 3x mentsuyu: 1 cup (240 ml) + cold water: 2 cups (480 ml) to dilute

Seasonal Tempura & Batter

• Neutral oil for frying: 1.5–2 quarts (1.5–2 L)
• Mixed vegetables: 12 oz (340 g), such as 1 small sweet potato (150 g, 1/4 in slices), 6 asparagus spears (90 g, trimmed), 6 shiitake mushrooms (100 g, stems removed)
• Optional: 8 large shrimp (about 10 oz / 280 g), peeled/deveined, tails on
• Large egg: 1, cold
• Ice-cold sparkling water: 1 cup (240 ml)
• Cake or all-purpose flour: 1 cup (120 g), plus 2 tbsp for dusting shrimp/veg
• Cornstarch: 2 tbsp (16 g)
• Baking powder: 1/4 tsp
• Kosher salt: 1/2 tsp, plus more for finishing

Step-by-Step Instructions

Step 1: Make the tsuyu (dipping sauce)

Homemade: Add 3 cups (720 ml) water and the kombu to a small pot. Heat gently to just below a simmer (about 190°F / 88°C) for 10 minutes; do not boil. Remove kombu, bring to a bare simmer, add katsuobushi, turn off heat, and steep 3 minutes. Strain to yield about 2 cups (480 ml) dashi. Return to the pot with 1/2 cup (120 ml) soy sauce, 1/2 cup (120 ml) mirin, and 1 tsp (4 g) sugar. Simmer 2 minutes, cool, then chill at least 20 minutes.

Shortcut: Mix 2 tsp instant dashi with 2 cups (480 ml) hot water, then proceed with soy, mirin, and sugar as above. Or dilute 1 cup (240 ml) 3x mentsuyu with 2 cups (480 ml) cold water and chill.

Step 2: Prep garnishes and vegetables

Thinly slice the scallions and cut the nori into fine ribbons. Prep vegetables: sweet potato into 1/4 in (6 mm) rounds, asparagus trimmed, shiitake stems removed. Pat everything very dry so the batter adheres. If using shrimp, pat dry and score the belly side with 3 shallow slashes to keep them straight.

Step 3: Heat oil and mix a cold, light tempura batter

Pour 1.5–2 in (4–5 cm) of neutral oil into a deep, heavy pot. Heat to 350°F (175°C). Set a wire rack over a baking sheet and warm the oven to 250°F (120°C) for holding. In a medium bowl over an ice bath, lightly beat the cold egg, whisk in 1 cup (240 ml) ice-cold sparkling water. Sprinkle in 1 cup (120 g) flour, 2 tbsp (16 g) cornstarch, 1/4 tsp baking powder, and 1/2 tsp salt. Stir with chopsticks 8–10 strokes—leave it lumpy and streaky for crispness.

Step 4: Fry the tempura

Dust vegetables and shrimp lightly with flour. Dip a few pieces into the batter and fry in small batches for 1–2 minutes, flipping once, until pale golden with a delicate, craggy crust. Maintain oil at 340–355°F (171–179°C). Transfer to the rack, sprinkle with a pinch of salt, and keep warm in the 250°F (120°C) oven. Skim loose batter bits between batches.

Step 5: Cook the soba and chill

Bring 3 quarts (3 L) of water to a rolling boil. Add soba and stir. Boil 4–5 minutes (check your package; taste at 4 minutes). Reserve 1 cup (240 ml) of the cooking water (soba-yu), then drain. Rinse noodles under cold running water, rubbing gently to remove starch until the water runs mostly clear, 45–60 seconds. Transfer to an ice bath for 1 minute, drain well, and mound on a bamboo mat, sieve, or towel-lined tray.

Step 6: Plate and portion

Divide noodles among plates/mats and top with nori ribbons. Pour chilled tsuyu into small bowls or cups (about 1/2 cup / 120 ml per person). Set out scallions and wasabi on the side. Arrange tempura on a warm plate lined with paper.

Step 7: Eat the zaru soba the traditional way

Stir a little wasabi and scallions into your tsuyu to taste. Using chopsticks, pick up a small bundle of soba, dip briefly, and slurp. Dip tempura into the same tsuyu. To finish, warm your leftover tsuyu by adding a splash of hot soba-yu (start with 1/4 cup / 60 ml) and sip as a light broth.

Pro Tips

• Keep the batter cold—use an ice bath and work fast. Cold batter meeting hot oil makes the crispiest tempura.
• Do not overmix the batter. Visible lumps and a few dry streaks are ideal for a delicate, lacy crust.
• Rinse and rub the soba well to remove surface starch; this is the key to springy, non-gummy noodles.
• Use a bamboo mat (zaru) or a mesh sieve to serve; airflow keeps noodles dry and pleasantly cool.
• Make tsuyu 1–3 days ahead; it tastes rounder after a night in the fridge.

Variations

• Vegetarian/vegan tsuyu: Make dashi with 3 cups water, 10 g kombu, plus 2 dried shiitake caps; steep 30 minutes off heat, then proceed (no bonito).
• Gluten-free: Use 100% buckwheat soba (juwari) and gluten-free tamari; check dashi and mentsuyu labels. Batter with a gluten-free flour blend.
• Spicy-citrus twist: Add 1/2 tsp yuzu kosho or a squeeze of fresh yuzu/lemon to the tsuyu just before serving.

Storage & Make-Ahead

Tsuyu keeps 1 week refrigerated in a sealed jar; up to 2 months if frozen. Tempura is best fresh; re-crisp on a rack at 375°F (190°C) for 5–7 minutes. Cooked soba is best eaten within 2 hours; if needed, store rinsed noodles in cold water up to 8 hours, drain very well, and refresh briefly in ice water before serving.

Nutrition (per serving)

Approximate for 1 of 4 servings with vegetable tempura (no shrimp): 650 calories; 20 g protein; 88 g carbohydrates; 22 g fat; 4 g fiber; 1,800 mg sodium. Values vary with vegetable mix, frying oil absorption, and tsuyu consumption.