Marinate the protein:
Toss the chicken (or beef, shrimp, or tofu) with the mirin and soy sauce in a medium bowl.
Make the stir-fry sauce:
Meanwhile, whisk together the mirin, chicken stock, oyster sauce, soy sauce, chile paste, sesame oil, garlic, cornstarch, and sugar in another medium bowl.
Make the stir-fry:
Heat 1 tablespoon of the oil in a large skillet over high heat until shimmering and wisps of smoke rise from the oil. Add half of the protein and cook, stirring often, until lightly browned, about 2 minutes, then transfer to a plate. Repeat with the remaining protein.
Add 1 tablespoon of the oil to the pan and, once it shimmers, add the carrots, broccoli, and ¼ cup water. Cover and cook until the broccoli is bright green, about 1 minute. Uncover and cook, stirring constantly, for 1 minute.
Using a spatula, push the carrots and broccoli to the edge of the pan. Add the bok choy ribs and the onion to the center of the pan and cook, stirring often, for 1 to 2 minutes.
Push the bok choy ribs and the onion to the edge of the pan. Add the bok choy leaves and snow peas to the center of the pan and cook, stirring often, for 1 minute.
Push the bok choy leaves and snow peas to the edge of the pan. Add the remaining 1 tablespoon oil, the garlic, and ginger to the center of the pan and cook until fragrant, 30 to 45 seconds. Stir the garlic and ginger into the vegetable mixture until combined.
Return the protein to the pan and toss to combine. Pour the sauce around the edge of the pan and toss to combine. Serve over rice and sprinkled with bean sprouts.
By cutting vegetables on the bias, you expose more surface area to the heat so it cooks faster.