Combine soy sauce, mirin, sake, and sugar in a bowl and stir to combine. Add the salmon and marinate for 15 minutes.
2. Step
For the sauce, combine soy sauce, mirin, sake, and sugar in a bowl and stir to combine.
3. Step
Heat a pan over medium-high heat and add a splash of salad oil. Add the marinated salmon and cook until both sides are cooked through, about 3 minutes.
4. Step
Add the reserved marinade to the pan. Stir until the salmon is fully coated in the glaze.
5. Step
Form the rice into four patties.
6. Step
Heat another pan over medium-high heat and add the sesame oil. Add the rice “buns” and cook until the outside is crispy, about 5 minutes.
7. Step
Top the rice "bun" with a piece of green leaf lettuce, salmon, mayonnaise, and top with another rice “bun.” Repeat with remaining ingredients.
