Peel and cut the potato into 1/2-inch cubes and place them in a pot with water and a large pinch of salt. Bring to a boil, reduce to a simmer, and cook for 15 minutes, or until easily pierced with a knife. Drain and mash with a fork, 1 tablespoon butter, and a splash of water (or milk, if handy). Season with salt and pepper.

Meanwhile, core, seed, and devein the bell peppers, then thinly slice. Halve, peel and thinly slice the onion. Mince or grate the garlic. Strip the leaves off the thyme sprig. Finely chop the parsley.

Heat 1/2 tablespoon of olive oil in a pan over medium heat. Season each chicken breast with salt and pepper. Sear for 2-3 minutes on each side, until golden brown. Set aside.

In the same pan you cooked the chicken in, heat another 1/2 tablespoon olive oil over medium heat. Add the onions and peppers and season with salt and pepper. Cook for about 6 minutes, until slightly softened. Add the thyme leaves and garlic and cook for 30 seconds, until fragrant.

Add the diced tomatoes, 1/2 cup water, and stock concentrate. Season with salt and pepper and bring to a boil. Reduce to a simmer and nestle the chicken in the sauce. Cook for about 4 minutes, until chicken is cooked through and no longer pink in the middle.

Serve the mashed potatoes with a chicken breast to the side. Top with a spoonfull sauce and a sprinkle of parsley.