Preheat your grill or grill pan to medium-high heat.
Season the flank steak with salt, pepper, and a touch of garlic powder if desired.
Toss the zucchini, bell peppers, and red onion with one teaspoon of olive oil and a pinch of salt.
Place the steak on the grill and cook for approximately 4-5 minutes per side for medium-rare, or until it reaches your preferred level of doneness.
At the same time, place the vegetables on the grill and cook until they have nice char marks and are tender-crisp, about 6-8 minutes.
Remove the steak from the grill and let it rest on a cutting board for at least 5 minutes to keep the juices intact.
While the steak rests, whisk together the remaining teaspoon of olive oil and the lemon juice with fresh herbs like parsley or oregano.
Slice the steak thinly against the grain.
Assemble your bowl by placing the cooked quinoa at the base, then topping with the grilled vegetables and sliced steak.
Drizzle the lemon-herb vinaigrette over the entire bowl before serving.