Mix the marinade. In a bowl, whisk balsamic vinegar, olive oil, maple syrup or honey, garlic, Dijon, Italian seasoning, salt, pepper, and red pepper flakes if using.

Prep the chicken. Pat chicken dry and slice large breasts horizontally to create cutlets about 1/2 to 3/4 inch thick. This helps them cook evenly and stay juicy.

Marinate briefly. Add chicken to a zip-top bag or bowl, pour in 2/3 of the marinade, and toss to coat. Set aside for 15–30 minutes at room temp while you prep veggies. Reserve the remaining marinade for glazing.

Preheat and prep veggies. Heat the oven to 425°F (220°C). Toss broccoli, bell pepper, and red onion with a drizzle of olive oil, a pinch of salt, and pepper. Spread on a sheet pan in a single layer.

Roast vegetables. Roast for 18–22 minutes, tossing once, until the edges char slightly and the veggies are crisp-tender. If using cherry tomatoes, add them in the last 8–10 minutes so they blister but don’t collapse.

Cook the chicken. Heat a large skillet or grill pan over medium-high. Lightly oil the surface. Shake off excess marinade and cook chicken 4–5 minutes per side, depending on thickness, until browned and the internal temperature hits 165°F (74°C).

Glaze and rest. Reduce heat to medium-low. Pour the reserved marinade into the pan and let it simmer for 1–2 minutes, stirring, until slightly syrupy. Turn chicken to coat. Transfer to a plate and rest for 5 minutes, then slice.

Assemble the plates. Add a base of quinoa, brown rice, or farro to each container. Top with roasted veggies and sliced balsamic chicken. Spoon extra glaze from the pan over the chicken.

Finish and store. Sprinkle with chopped herbs, a pinch of flaky salt, and black pepper. Add Parmesan or feta if you like. Let cool uncovered for 15–20 minutes, then seal and refrigerate.