Combine rinsed lentils and vegetable broth in a large stockpot and bring to a rolling boil.

Reduce heat to medium-low, cover, and simmer for 15 minutes.

Add the cubed potatoes to the pot and continue to simmer for 10 minutes until the lentils and potatoes are nearly tender.

Heat olive oil in a skillet over medium heat and sauté the diced onion until translucent, approximately 5 minutes.

Add the minced garlic and ground cumin to the skillet and cook for 60 seconds until aromatic.

Incorporate the onion and garlic mixture into the stockpot.

Add the chopped Swiss chard to the soup and cook for 5 to 8 minutes until the greens are wilted and tender.

Remove the pot from the heat and stir in the fresh lemon juice, salt, and black pepper.

Stir in fresh cilantro and serve immediately.