Wash the tilapia fillets and pat dry. Season both sides of tilapia fillets with black pepper and salt (if the pesto sauce is not salty).
Preheat oven to 390 degrees F. Grease the bottom of a baking dish lightly with cooking spray. Place the tilapia fillet in the baking dish. Mix the basil pesto sauce and sour cream and spread all over the fillets.
Place on the middle rack of the oven and bake until cooked through, about 15-17 minutes. Serve tilapia pesto dish immediately.