Preheat oven to 180 degrees C. Peel the beetroot and cut into 1cm cubes. Mix with 1 teaspoon olive oil and add salt and pepper to taste. Place in a baking pan and bake 35 minutes, turning a couple of times.
In the meantime, place the lentils in a saucepan with the carrot, onion, bay leaf, parsley and thyme. Add water to cover the lentils. Cover and simmer for 25 minutes until the lentils are tender but not soft.
Drain the lentils and combine with the beetroot in a salad bowl.
To make the dressing, combine the lemon juice, olive oil, lemon zest, fresh chopped herbs and salt and pepper as desired. Toss with the salad.