1. Cut chicken in strips and sauté in butter for 2 minutes. Do not cook the meat too long, otherwise it dries out.
2. In a large skillet heat the oil and add the onion, garlic, and parsley; sauté a few seconds. Add the carrot and sauté 2 minutes at high heat. If the vegetables start to burn, add 2 tablespoons of water to the pan.
3. Add the chicken and cook 30 seconds more. Add salt, watercress or spinach and pepper; heat 1 minute. Serve immediately.