Heat oil over medium in a skillet. add onions and garlic and cook over medium-low for 15-20 minutes until partially caramelized.
While these cook, bring stock to a boil. Once boiling, add lentils. Cook 10 minutes.
Use 1/4 cup stock from pot to blend onions into a puree.
Add onion puree and spices to the pot, stirring well. Cook together for 3 minutes.
Add chard, stirring to submerge, then cover and cook 5-7 minutes more until chard is wilted and flavors have mingled.
Use an immersion blender - or transfer 2 cups at a time to the food processor - and blend until smooth.
Add additional salt and pepper to taste. Serve.