Combine ½ cup dashi (Japanese soup stock), 2 Tbsp soy sauce, 2 Tbsp mirin, and 2 tsp sugar in a bowl or a liquid measuring cup and mix all together until the sugar is dissolved.

Slice ½ onion lengthwise, about ¼ inch wide.

Trim the extra bits of fat and connective tissue from 10 oz boneless, skinless chicken thighs with the knife.

Cut the chicken thigh along the grain into strips ¾–1 inch (2–2.5 cm) wide. Next, angle your knife back and diagonally (nearly parallel to the cutting board), and then slice the chicken strips against the grain into pieces about ¾–1 inch (2–2.5 cm) square.

Transfer the chicken to a bowl or tray and sprinkle with 1 Tbsp sake. Set aside for 5 minutes.

Crack 3-4 large eggs (50 g each w/o shell) into a bowl. Using a pair of chopsticks, lift the egg whites to “cut“ them 5–6 times into a few smaller clumps. This will prevent the egg whites from falling into the frying pan all at once. Do not whisk or beat the eggs together. The eggs should resemble a marble pattern.

With the stove off, add the sliced onions to a medium frying pan in a single layer. Then, add the seasonings mixture. It should just cover the onions. If not, your frying pan is too big and you need to either increase the seasoning or use a smaller pan.

Turn on the heat to medium and bring it to a simmer. Once simmering, add the chicken on top of the onions.

Make sure the onions and chicken are evenly distributed. Once simmering again, lower the heat to medium low. Cook, uncovered, for 5 minutes or until the chicken is no longer pink and the onions are tender. Halfway through, flip the chicken.

Increase the heat to medium. With the cooking liquid simmering (small bubbles around the edges), drizzle two-thirds of the eggs in a circular pattern over the chicken and onions, avoiding the edges of the pan where the eggs can easily overcook.

When the eggs are still runny but just set, add the rest of the eggs to the center and around the edges of the pan. Add the green onion on top and cook on medium low until the egg is done to your liking.

Serve steamed rice in individual serving bowls. Spoon the cooked chicken and egg mixture onto the steamed rice and drizzle the desired amount of pan sauce on top.

You can keep the leftovers in an airtight container and store in the refrigerator for up to 2–3 days.