How to Make It
In a large saucepan, cover the kombu with 4 cups of water and bring to a boil. Reduce the heat and simmer gently for 30 minutes. Remove the pan from the heat and stir in the bonito flakes; let stand at room temperature for 1 hour. Strain the dashi into a bowl and let cool to room temperature.
In a food processor, combine the egg yolks, lemon juice, Dijon mustard, vinegar, garlic, togarashi, Tabasco and cheese and pulse to combine. With the machine on, drizzle in the rice bran oil, then drizzle in 1/4 cup of the dashi until incorporated (reserve the remaining dashi for another use). Season with salt.