Step 1: Cook the Vegetables
Heat 1 teaspoon of oil in a large skillet over medium heat.
Add the broccoli and mushrooms, cooking for about 4 minutes until they are just tender.
Toss in the ginger and garlic, cooking for another 30 seconds to bring out their aroma.

Step 2: Set Aside the Vegetables
Remove the vegetables from the pan and set them on a plate.
Cover lightly to keep them warm while you cook the chicken.
Wipe the skillet clean with a paper towel to remove any residue.

Step 3: Cook the Chicken
Turn the heat to high and add the remaining tablespoon of oil.
Season the chicken pieces with salt and pepper and place them in the pan in a single layer.
Cook for about 3-4 minutes per side until the chicken is golden brown and fully cooked.

Step 4: Combine Everything
Add the cooked vegetables back into the pan with the chicken.
Cook together for another 2 minutes, allowing the flavors to meld and the veggies to reheat.
Stir gently so everything gets well combined.

Step 5: Make the Sauce
In a bowl, whisk together the oyster sauce, chicken broth, sugar, sesame oil, and soy sauce.
In a smaller bowl, mix the cornstarch with a tablespoon of cold water.
Pour the sauce over the chicken and vegetables, then add the cornstarch slurry.

Step 6: Finish the Stir Fry
Bring everything to a gentle boil and cook for about 1 minute until the sauce thickens.
Once the sauce has beautifully coated the chicken and veggies, remove from heat.
Serve immediately, ideally over fluffy steamed rice.