In a heavy bottomed stovetop-to-oven pot, heat olive oil over medium heat. Add onion and saute for 5 minutes, stirring occasionally.
Toss in minced garlic and thyme leaves. Cook for an additional minute, then pour in lentils and stock.
Add the bay leaf and bring to a boil. Meanwhile, grate the beets on the large side of a box grater and add to the pot. Stir well to combine.
When the lentils have reached the boiling stage, remove from heat and place in the middle rack of the oven. Cook for 50-60 minutes, or until lentils are tender. There will still be a little liquid, but it will be absorbed.
Remove braised lentils from the oven; stir in the salt and vinegar. TAste and adjust seasoning to taste.
Spoon into bowls. Top with grated or julienne apple, a spoonful of sauerkraut and a sprinkling of goat cheese. Enjoy at once.