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How to Make Udon Noodle Soup

Name: How to Make Udon Noodle Soup
Yield: 4
Ingredients: 2 tsp instant dashi powder; 4 cups hot water; 4 inch kombu; 1 cup bonito flakes; 3 tbsp soy sauce; 1 tbsp mirin; 1 tsp salt; fresh udon noodles; green onions; soft-boiled egg; tempura; kamaboko

Udon soup starts with dashi broth—either from scratch with kombu and bonito flakes or from quality instant powder. Cook fresh or frozen udon noodles separately, then combine with hot broth and your choice of toppings like green onions, tempura, or soft-boiled eggs. The key is keeping the broth clear and the noodles from getting mushy.

Total time: 45 min
Hands-on: 20 min
Serves: 4
Difficulty: Easy

Ingredients

2 tsp instant dashi powder
4 cups hot water
4 inch kombu
1 cup bonito flakes
3 tbsp soy sauce
1 tbsp mirin
1 tsp salt
fresh udon noodles
green onions
soft-boiled egg
tempura
kamaboko

Step by step

Make the dashi broth. If using instant dashi powder, dissolve 2 teaspoons in 4 cups hot water. For homemade dashi, steep a 4-inch piece of kombu in cold water for 30 minutes, bring to a gentle simmer, add 1 cup bonito flakes, steep 5 minutes, then strain.
Season the broth. Add 3 tablespoons soy sauce, 1 tablespoon mirin, and 1 teaspoon salt to the warm dashi. Taste and adjust—the broth should be savory but not overpowering since the noodles will absorb some flavor.
Cook the udon noodles. Bring a separate pot of water to a rolling boil. Add fresh udon and cook for 2-3 minutes, or frozen udon for 1 minute. Drain immediately and rinse briefly with cold water to stop the cooking and remove excess starch.
Warm the noodles. Place the drained noodles in your serving bowls and pour a small amount of hot broth over them to warm them through. This prevents the noodles from cooling down the entire bowl of soup.
Assemble and serve. Ladle the hot seasoned broth over the noodles, leaving room for toppings. Add sliced green onions, a soft-boiled egg, tempura, or kamaboko. Serve immediately while the broth is steaming.

Tips & troubleshooting

Never overcook udon noodles—they should have a firm, chewy texture that holds up in the hot broth
Keep extra broth hot in a small pot so you can top off bowls as the noodles absorb liquid
Rinse cooked noodles quickly to remove surface starch that would cloud your clear broth
Warm your serving bowls with hot water before adding the noodles and broth
Cut green onions on the bias and use both white and green parts for different textures

Variations

Kitsune Udon. Top with sweet seasoned fried tofu pockets (aburaage). Simmer the tofu in a mixture of dashi, soy sauce, sugar, and mirin until glossy.
Tempura Udon. Serve with hot tempura on top—shrimp tempura is classic, but vegetable tempura works well too. The tempura will soften slightly in the broth.
Beef Udon. Add thinly sliced beef that you've quickly simmered in the seasoned broth until just cooked through. The beef should be tender and lightly flavored by the broth.
Cold Udon. Serve chilled noodles on a bamboo mat with cold dipping sauce (tsuyu) made from concentrated dashi, soy sauce, and mirin on the side.

Questions

Can I use dried udon noodles instead of fresh or frozen?: Yes, but they need longer cooking time—usually 8-10 minutes. Follow the package directions and test for doneness. Dried noodles won't have quite the same chewy texture as fresh.
How do I store leftover udon soup?: Store the broth and noodles separately in the refrigerator. The noodles will absorb liquid and become mushy if left in the broth. Reheat the broth and pour over the cold noodles to warm them.
What if I can't find dashi ingredients?: Look for instant dashi powder in the Asian section of grocery stores or online. Chicken or vegetable broth will work in a pinch, though the flavor will be different from traditional dashi.
Can I make this ahead of time?: Make the broth ahead and reheat it, but cook the noodles fresh when serving. Udon noodles don't hold well once cooked—they become soft and lose their characteristic chew.