Preheat your grill or grill pan over medium-high heat.
Season the chicken breast with salt, pepper, and a drizzle of olive oil. Squeeze a bit of lemon juice over it for extra zest.
Grill the chicken breast for about 6-7 minutes per side or until the internal temperature reaches 165°F. Remove from grill and let rest.
While the chicken is grilling, rinse the quinoa under cold water. In a small saucepan, combine the quinoa with water (use a standard 2:1 liquid to quinoa ratio) and bring to a boil. Reduce heat, cover, and simmer until water is absorbed (about 15 minutes).
Preheat the oven to 425°F. Toss the chopped mixed bell peppers and zucchini with a splash of olive oil, salt, and pepper. Spread them on a baking sheet and roast for about 15 minutes until tender and slightly caramelized.
For the finishing touch, mix the Greek yogurt with a dash of lemon juice and a pinch of salt to create a light, tangy sauce.
Plate the sliced grilled chicken over a bed of quinoa, add the roasted vegetables on the side, and drizzle with the Greek yogurt sauce. Serve warm and enjoy!