This spicy, tangy side dish is great alongside Asian chicken and chili soup.
In a large pot of boiling salted water, cook baby broccoli until just tender, 12 to 15 minutes; drain. Transfer to a serving bowl.
Meanwhile, in a small skillet, combine orange juice, shallots, vinegar, and pepper flakes, if using; simmer over medium heat until reduced to 1/4 cup, 3 to 4 minutes. Spoon sauce over baby broccoli; toss gently.
If you can't find baby broccoli, substitute 1 pound regular broccoli. Trim tough stem ends, and cut broccoli lengthwise.