Season the chicken breasts with salt, pepper, and half the oregano. Heat 1 tablespoon of olive oil in a large skillet or Dutch oven over medium-high heat. Cook chicken for 6 to 7 minutes per side until golden brown and cooked through to an internal temperature of 165°F. Remove chicken and set aside to rest.

In the same pan, add the remaining tablespoon of olive oil. Add the chopped red onion and cook for 2 to 3 minutes until softened. Add the minced garlic and cook for 30 seconds until fragrant. Keep an eye on the heat to prevent the garlic from burning.

Add the diced bell pepper and zucchini to the pan and cook for 3 to 4 minutes until they begin to soften. Pour in the dry orzo pasta and stir to coat with the oil and vegetables.

Pour in the chicken broth and bring to a boil. Reduce heat to medium-low, cover, and simmer for 10 to 12 minutes, stirring occasionally, until the orzo is tender and has absorbed most of the liquid. If liquid absorbs too quickly, add a splash more broth or water.

Slice the rested chicken into strips. Add the cherry tomatoes, balsamic vinegar, and remaining oregano to the pan. Gently fold in the sliced chicken and cook for 2 to 3 minutes until the tomatoes are warmed through and the balsamic forms a light glaze.

Remove from heat and garnish with fresh basil leaves. Serve immediately while hot.