Preheat the oven to 450°F (230°C).
Toast the sliced almonds: heat a small skillet over medium and spread the 1/2 cup almonds in an even layer. Stir frequently until lightly golden and aromatic, then transfer to a cool bowl to stop cooking. Reserve most; set aside 1/4 cup for the pesto and a few tablespoons for garnish.
Season the salmon fillets on both sides with salt and black pepper.
Heat a large oven-safe nonstick skillet over high heat. Add a thin layer of olive oil and heat until hot and just below smoking.
Sear the salmon fillets, crust side down, for 2–3 minutes until a golden-brown crust forms.
Without flipping, transfer the skillet to the preheated oven and roast the salmon 5–10 minutes, depending on thickness, until cooked to your preferred doneness. Use an oven mitt when handling the hot skillet.
While the salmon cooks, make the almond pesto: place 1/4 cup of the toasted almonds in the food processor and pulse until finely ground.
Add the basil leaves, Meyer lemon juice, minced garlic, and 1/4 teaspoon salt to the processor. Process until the basil is finely chopped, scraping the sides as needed.
With the processor running, slowly drizzle in about 5–6 tablespoons of olive oil through the feed tube over 2–3 minutes until the mixture emulsifies and becomes creamy. Scrape down sides and process a few more seconds; adjust seasoning with more salt if desired.
To serve, spread about 1 tablespoon pesto in a circle on each plate. Place a seared salmon fillet on top, dollop another tablespoon of pesto over the fillet, and sprinkle with the reserved toasted sliced almonds.