Rinse the quinoa under cold water. Combine it with the water in a medium saucepan, add a pinch of salt, and bring to a boil. Reduce heat to low, cover, and simmer for 15 minutes until the water is absorbed. Remove from heat and let it sit covered for 5 minutes.

While the quinoa cooks, season both sides of the chicken breasts with salt and pepper. Heat 1 tablespoon olive oil in a large skillet over medium heat. Add the chicken and cook for 6 to 7 minutes per side until golden and cooked through.

Add the remaining tablespoon of olive oil to the skillet. Scatter the halved cherry tomatoes around the chicken and cook for 2 minutes until they soften slightly.

Lay the mozzarella slices over the chicken breasts. Cover the skillet for 2 minutes to let the cheese melt.

Fluff the quinoa with a fork and stir in 2 tablespoons balsamic vinegar. Spoon the quinoa onto plates, top with the chicken and tomatoes, then scatter basil leaves over everything. Drizzle the remaining balsamic vinegar on top before serving.