Chop the onion, celery, carrot, and garlic. Cut the tempeh into bite-sized pieces.
Heat a little oil in a pan and cook the onion, celery, and carrot for about 10 minutes, until softened.
Add the garlic, vinegar, and oregano, and cook for another minute.
Stir in the lentils and chopped tomatoes. Fill the tomato tin with water and add enough to just cover the vegetables, then add the stock cube.
Simmer for about 10 minutes.
Add the kale and cook for another 5 minutes, until wilted.
Stir in the tempeh and cook briefly until heated through.
Serve hot with brown rice or wholemeal pasta.