1 1/2 pounds broccoli
2 teaspoons vegetable oil
1/4 cup plus 3 tablespoons water
3 tablespoons soy sauce
1 tablespoon cornstarch
1 tablespoon packed light brown sugar
1/4 teaspoon red pepper flakes
3 medium garlic cloves, finely chopped
1 teaspoon toasted sesame seeds
Trim about 1 inch off the stem ends of the broccoli. Using a vegetable peeler, peel away the woody outer layer of the stalks. Halve the broccoli lengthwise through the stem and florets. Turn the pieces so that they are cut-side down, then cut them lengthwise through the stem and florets into 1/2-inch-wide pieces. Cut those pieces crosswise into 1-inch pieces; set aside.
Heat the oil in a large nonstick frying pan over medium-high heat until shimmering. Add the broccoli and stir to coat in the oil. Add 3 tablespoons of the water and cover with a tightfitting lid. Cook until the broccoli is crisp-tender, about 3 minutes.
Meanwhile, place the remaining 1/4 cup water, soy sauce, cornstarch, sugar, and red pepper flakes in a medium bowl and whisk to combine; set aside.
Reduce the heat to medium, add the garlic to the frying pan, stir to combine, and cook until fragrant, about 1 minute.
Remove the pan from the heat. Rewhisk the reserved sauce and add it to the pan. Stir until the sauce thickens and coats the broccoli, about 1 minute. Stir in the sesame seeds and serve immediately.