In a large bowl, add the beef strips and 4 tablespoons of the Asian Peanut Sauce and toss to coat the meat.
Cover the bowl and refrigerate for at least 30 minutes or up to overnight.
In a medium pot over high heat, bring the water to a boil.
Stir in the quinoa and reduce the heat to medium-low.
Cover and simmer the quinoa, stirring occasionally, until the liquid is absorbed and the grains are tender, about 15 minutes.
Transfer the quinoa to a large bowl and let cool lightly.
In a large wok or skillet over medium heat, heat the oil until it shimmers.
Add the beef and cook until it is browned on all sides, about 8 minutes.
Discard the leftover beef marinade.
Add the broccoli, bell pepper, and snow peas, stirring occasionally, until the vegetables have started to soften, about 8 minutes.
Add the remaining 2 tablespoons of Asian Peanut Sauce to the stir-fry and cook, stirring frequently, until heated through, about 2 minutes.