Cook green beans the day before the party. Pat dry with paper towels, and store in a zip-top plastic bag.
Cook green beans in boiling salted water to cover in a Dutch oven over medium-high heat 4 to 5 minutes or until crisp-tender. Drain and plunge into ice water to stop the cooking process; drain.
Sauté peppers in hot oil in a Dutch oven over medium-high heat 5 minutes or until tender. Add green beans, basil, and salt. Cook, stirring constantly, until thoroughly heated. Serve immediately.