In a medium saucepan, combine the rinsed quinoa and vegetable broth. Bring to a boil, then reduce heat to low, cover, and let simmer for about 15 minutes until quinoa is fluffy and liquid has been absorbed. Remove from heat and let it sit covered for an additional 5 minutes.
Fluff the quinoa with a fork and set aside.
In a large skillet or wok, heat the sesame oil over medium-high heat. Add the diced onion and sauté for 2-3 minutes or until translucent.
Stir in the minced garlic and grated ginger, cooking for an additional minute until fragrant.
Add the diced carrot and red bell pepper; cook for 3-4 minutes, until the vegetables start to soften.
Toss in the snap peas and spinach, stirring well. Cook for another 2-3 minutes until the spinach wilts and snap peas are tender-crisp.
Add the cooked quinoa to the skillet, pour in the soy sauce and rice vinegar, and stir everything together gently. Cook for another 2-3 minutes until heated through.
Season with salt and pepper to taste, adjusting flavors as needed.
Remove from heat and garnish with chopped green onions and sesame seeds before serving.