In a medium bowl, combine the steak with the cornstarch. Toss to coat.
Heat 2 tablespoons of the avocado oil in a cast-iron skillet or wok over medium-high heat.
When the oil shimmers, working in batches, add the steak and cook until browned, 2 minutes per side. Transfer the steak to a plate.
To the same skillet, add 1 tablespoon of the oil and the broccolini. Cook, stirring occasionally, until bright green and tender, 4-5 minutes. Transfer the broccolini to the plate with the steak.
Reduce the heat to medium. Give the pan a minute to adjust. Add the remaining 1 tablespoon oil, the garlic, ginger, and Sambal Oelek. Cook until fragrant, about 1 minute. Add 1/4 cup of water, the soy sauce, and the honey. Increase the heat to medium-high and bring to a boil. cook until slightly thickened, 3-5 minutes. Return the steak and broccolini to the pan, tossing to coat in the sauce. Cook until warmed through, 1-2 minutes. Stir in the green onions.
To serve, spoon the beef and broccolini over the rice. Sprinkle with toasted sesame seeds and more green oinion.