Create a dry brine mixture in a bowl, combining the sugar & salt. Remove salmon from fridge. Dust both sides of each filet with the brine. Let salmon rest on counter for 10 minutes. Once the time is up, rinse off the salmon and pat very dry.
Make teriyaki sauce. Combine ¾ of the water, soy sauce, brown sugar, honey, rice vinegar, ginger powder & garlic powder in a small pot on low heat. Stir occasionally for 7-10 mins.
In a small bowl whisk together the remaining ¼ cup cold water and cornstarch. Pour mixture into the pot and whisk frequently until it's the thickness you like. (I let it thicken while I set the table). Remove from heat.
Heat a medium/large pan on medium heat. Wait until it gets super hot and then pour in the sesame oil. Make sure your salmon is very dry. Then, place salmon filets, skin side down, onto the pan. (You might need to cook the filets in 2 batches). Immediately turn the temp to low. Cook the salmon until you see that the dark pink coloring has turned to light pink about ½ to ¾ of the way up the filet. (For me, this took like 3 ½ mins). Then flip the fish and cook for 1-2 mins on the other side. When the salmon is cooked through, remove from heat.
Notes
Dry the salmon completely before it goes in the pan. Otherwise, it will stick.
Note on temperature: heat the pan until it's very hot and then add the oil. Once the oil is heated, add the fish and immediately turn the temperature down. This will provide for crispier skin and helps avoid overcooking. Salmon should be 125° F (definitely no higher than 140°).
Cook the salmon skin-side down for the majority of cooking time. The fat in the skin allows the fish to cook more evenly and also helps avoid overcooking.
This may go without saying, but watch out for fish bones. Salmon bones are thin, clear, and sometimes hard to see.