Slice tempeh crosswise into ½" strips. Place in bowl and toss with tamari and liquid smoke. Let marinate for at least 10 minutes.
Heat oil in pan at medium-high. Add onion and tempeh strips and sauté 7-10 minutes, flipping tempeh to brown on all sides.
Remove tempeh and onion from pan and set aside. Turn heat down to medium and lightly sauté kale until wilted (about 3-4 minutes).
Arrange each plate by spreading a layer of lentils on the bottom. Top with kale, then tempeh and onions, then avocado and finally sauerkraut. Sprinkle with salt and pepper.
Recipe by The Colorful Kitchen at https://thecolorfulkitchen.com/2015/01/22/lentil-tempeh-reuben-bowl-vegan-gluten-free/