Heat the olive oil and onion over medium heat.

When the onion starts to brown, add the garlic and sauté until fragrant, then set aside.

Rinse the lentils, then place them in a pot with 4 1/2 cups water (about 1.1 liters). Bring to a boil, then simmer for 10 minutes.

Add the sautéed onion and garlic, vegetable bouillon cube, salt, pepper, and cumin to the lentils. Cook for another 10 minutes.

Remove the soup from the heat, then stir in the parsley and lemon juice. Serve hot.