Bring a small pot of water to a boil and prepare a bowl of ice water. Blanch the basil leaves for 10–15 seconds, just until bright green, then immediately transfer to the ice bath to stop the cooking. Drain and gently squeeze out excess water. Blend the blanched basil with the olive oil and a pinch of sea salt until completely smooth and vibrant green. Strain through a fine sieve or cheesecloth (optional but recommended). Set aside.