Marinate beef strips:

Cut the beef across the grain into slices 1/4-inch (0.5 cm) thick or sticks 1/2-inch (1 cm) wide. Place in a small bowl. Add soy sauce, peanut oil, and cornstarch (plus baking soda if using). Mix gently with your hands until each piece has a thin coating. Let it marinate for 10 minutes while you prep the rest.

Whisk sauce ingredients:

In a medium bowl, whisk together all sauce ingredients: chicken stock, Shaoxing wine, soy sauce, dark soy sauce, brown sugar, and cornstarch. Set aside.

Steam broccoli:

Pour 1/4 cup water into a large nonstick skillet and bring to a boil over medium-high heat. Add broccoli and cover. Steam until tender-crisp and the water is gone, roughly 1 minute. Remove broccoli to a plate. If any moisture remains, wipe the pan clean with a paper towel held in tongs.

Sear steak:

Add 1 tablespoon oil and swirl to coat the bottom. Heat over medium-high until shimmering. Arrange steak in a single layer. Cook untouched for 30 seconds until the underside browns. Flip and cook the other side for a few seconds. Stir-fry until the exterior is lightly charred but the interior remains pink.

Sauté aromatics:

Toss in garlic and ginger. Stir briefly to release their aroma.

Combine and thicken:

Return broccoli to the skillet. Give the sauce a final stir to re-dissolve the cornstarch, then pour it in. Cook and stir until the sauce thickens, about 1 minute. Immediately transfer everything to a plate. Serve hot as a main dish.