Slice salmon into individual portions, about 4-6 ounces each filet and season with salt and pepper.
In a skillet, add olive oil and heat on medium-high and sear salmon flesh side down for 3 minutes until a brown crust forms.
Flip the salmon and cook for another minute on the skin side.
Remove from the pan and turn the heat to medium.
Add garlic, mirin, soy sauce, vinegar, dark soy sauce, and mix.
Allow sauce to simmer and reduce for one minute on medium heat, then add back the salmon skin side down to the pan.
Spoon the teriyaki sauce over the salmon and cook for another 2 minutes or until desired salmon temperature is achieved. Salmon is done at 145 degrees.
Remove the salmon from skillet and plate, spoon over more sauce on the salmon and garnish with sliced green onions.