Heat oil in a large pot. Add leeks, carrots, and mushrooms. Cook 5 minutes.
Add cumin, paprika, and turmeric. Stir in and cook 1 minute.
Pour in broth, water, lentils, and tomatoes with juices. Bring to a boil.
Reduce heat to a simmer. Cover the pot and cook 30 minutes until lentils are tender.
Add sausage, chard, thyme, lemon juice, and salt. Simmer 10 minutes to wilt chard and warm through.