- 4 (6×4-inch) pieces dried kombu
- 1 (1.2-ounce) package bonito flakes (about 3 cups)
- 1 teaspoon white or regular soy sauce
- Kosher salt
- 4 large eggs, beaten to blend
- 3 cups torn mature spinach leaves
- 1 scallion, thinly sliced
- Chili oil and lemon wedges (for serving)
- 2 layers of cheesecloth
- Bring kombu and 6 cups cold water to a bare simmer in a large saucepan over low heat. Remove from heat and let sit 10 minutes. Return to a bare simmer and add bonito flakes. Remove from heat and let sit 2 minutes. Strain dashi through a fine-mesh sieve lined with 2 layers of cheesecloth into a large bowl.
- Wipe out saucepan and pour in dashi. Add soy sauce; season with salt. Bring to a bare simmer over medium-low. Whisk quickly to create a vortex and gradually stream in eggs, pouring in about 1″ from edge of pan. Remove from heat and add spinach; stir until wilted. Divide among bowls. Top with scallion and drizzle with chili oil. Serve with lemon wedges.