Method:
Pickle the egg yolks: Place yolks into a small container with soy sauce, mirin, and kombu. Cover with a paper towel to keep them submerged. Chill for at least 4 hours (or up to 8 for a firmer yolk).
Make the butadon sauce: In a small pan, combine soy sauce, mirin, sake, sugar, and grated garlic. Simmer gently until slightly thickened. Stir occasionally and keep warm.
Prepare the pork: Pat pork dry and slice into steaks. Season with Maldon salt and black pepper.
Grill the pork: Heat a pan over medium-high heat. Grill pork for 2–3 minutes per side until browned and cooked through. Brush with sauce, then rest for 5 minutes. Optional: torch for a smoky finish. Slice thinly against the grain.
Assemble the bowl: Spoon rice into bowls. Top with sliced pork, a cured egg yolk, and garnish with nori, spring onions, and sesame seeds. Finish with a drizzle of sauce.
To enjoy: Break the yolk and mix it into the rice, it brings everything together beautifully.