In a large pot of boiling salted water, cook the corn for 3-4 minutes. Do not overcook. Drain and immerse it in very cold water to stop the cooking process. When the corn is cool, use a serrated knife to cut the kernels off the cob. Combine the kernels in a large bowl with the oil, vinegar, scallions, salt, and pepper. Cover and refrigerate until ready to serve.
Just before serving, toss in the fresh basil. Taste and adjust seasoning. If the salad tastes too tart, add a bit more oil; if it tastes bland, add a bit more vinegar or salt and pepper. A pinch of sugar also goes a long way if the corn isn’t as sweet as you’d like. Serve the salad cold or at room temperature.