Pat the salmon fillets dry with a paper towel and season generously with salt and pepper on both sides.
Heat the skillet over medium-high heat and add the oil, waiting until it shimmers and begins to lightly smoke.
Place the salmon fillets skin-side down into the hot skillet, pressing gently to ensure good contact, and let cook undisturbed for about 4-5 minutes until the skin is crispy and golden brown.
Flip the salmon carefully with a spatula and cook for another 3-4 minutes until the flesh is opaque and flakes easily with a fork.
Reduce heat to low and dollop the spicy mayo over each fillet, spreading it slightly with the back of a spoon if needed to cover the top.
Allow the spicy mayo to heat through for about 1-2 minutes, letting the flavors meld and the sauce slightly thicken.
Once the sauce is bubbling and edges are slightly charred, remove the skillet from heat and serve immediately, spooning excess sauce over the flaky, crispy salmon.