In a medium pot, add the quinoa and 1 ½ cups water. Cover and turn the heat to high to bring to a boil/rapid simmer, then reduce to low and simmer for 12-15 minutes, or until liquid is absorbed and quinoa is cooked. Fluff with a fork and let cool for a bit.
Heat up your grill over medium-high heat for at least 10 minutes.
In a medium bowl, toss the chicken with the oil, spices, salt, and pepper to coat. Add the chicken to one side of the grill and grill on each side for about 5 minutes or until cooked through.
In a large bowl, add the veggies and scallions (if using) and toss with the 2 tablespoons oil and ½ teaspoon salt. Arrange the veggies on the other side of the grill and grill, covered, for 5 minutes or until you have nice grill marks. You may want to reduce the heat a bit so they don’t get super burnt, depending on your grill. Check on the scallions after 2-3 minutes. Careful not to burn the scallions (if using), they will likely be ready before the veggies. Flip the veggies and repeat.
Transfer the chicken and veggies to a cutting board and chop the veggies up and thinly slice the chicken.
In the same large bowl that you used for the veggies, add the dressing ingredients and whisk to combine. Add the cooked quinoa and grilled veggies and toss to coat.
Serve topped with sliced chicken, cheese (if using), and herbs (if using). This is also yummy with pickled red onion on top!