1. In a small saucepan, bring oil, orange zest, and red-pepper flakes to a simmer over medium-high and cook 3 minutes. Remove chili-orange oil from heat and set aside. (To store, refrigerate cooled oil in an airtight container, up to 3 days.)

2. Working in 2 batches, in a large pot of boiling salted water, cook asparagus and green beans separately until bright-green and crisp-tender, 3 minutes. Transfer to a colander and rinse with cool water to stop the cooking.

3. In a large skillet, heat 1 tablespoon chili-orange oil over high. Add half the vegetables and cook, stirring often, until warmed through and tender, 3 minutes. Stir in half the basil, season with salt and pepper, and transfer to a platter. Repeat with 1 tablespoon oil and remaining vegetables and basil. Drizzle with remaining oil and orange juice and serve immediately.