- 3/4 cup Sanuki Sea Stock
- 3 tablespoons soy sauce (see Tips, below)
- 1 tablespoon sugar
- 2, 3, or 5-gram packet bonito flakes (katsuobushi; see Tips, below)
- 2 tablespoons lemon and/or lime juice
- 1 recipe fresh udon noodles or 8 to 10 ounces dried or semidried udon noodles , cooked and chilled
- 2 tablespoons white sesame seeds, freshly toasted (see Tips, below)
- 8 to 10 fresh chives, snipped, or 2 to 3 scallions, trimmed and finely chopped
- Place the stock, soy sauce, and sugar in a small saucepan and heat slowly until small bubbles appear around the rim. Stir to dissolve the sugar. Remove the saucepan from the heat and add the bonito flakes. Wait 2 minutes, then add the lemon and/or lime juice. Strain the mixture through a fine-woven muslin cloth- or coffee filter-lined colander. Chill the sauce for at least 20 minutes, or refrigerate up to several days.
- If the cooked noodles seem sticky or pasty, quickly rinse in cold water and drain well. Divide them among 4 shallow serving bowls. Garnish the noodles with sesame seeds and chives or scallions. Serve the chilled ponzu sauce on the side to drizzle on and toss in just before eating.