Press salmon fillets between paper towels to dry surfaces thoroughly. Season on all sides with salt and pepper.
Heat oil in a large stainless steel skillet over medium-high heat until shimmering.
Add salmon fillets, skin side down. Immediately reduce heat to medium-low.
Cook, pressing gently on back of fillets to ensure good contact between the skin and the pan, until skin is rendered and crisp, about 6 minutes.
If skin shows resistance when you attempt to lift with a spatula, allow it to continue to cook until it lifts easily.
Flip salmon and cook on second side until a thermometer inserted into the thickest part registers 120°F (49°C) for medium-rare or 130°F (54°C) for medium, about 1 minute longer.
Transfer salmon to a paper towel–lined plate to drain.
Divide rice evenly between 4 serving bowls.
Top with diced avocado, cucumber, and scallions.
Top each with a salmon fillet and spoon sauce on top, using the back of a spoon to evenly glaze each fillet.
Sprinkle with furikake and/or sesame seeds. Serve immediately.
