Step 1

Heat 2 tablespoons oil in heavy large skillet over high heat. Add broccolini; sauté 1 minute. Add 1/4 cup water; cook, turning with tongs, until broccolini is crisp-tender, about 5 minutes. Transfer to bowl and set aside.

Step 2

Add remaining 2 tablespoons oil to same skillet and heat over medium-high heat. Add onion; sauté until soft and beginning to brown, about 4 minutes. Add chiles and garlic; stir 30 seconds. Add remaining 1/4 cup water, fish sauce, sugar, and pepper. Return broccolini to skillet and cook, stirring occasionally, until heated through. Season with salt and pepper.