Heat the olive oil in a large pot over medium heat. Add the garlic, onion, and carrots and cook for about 3-5 minutes, stirring occasionally, until softened.
Add the cumin, salt, and black pepper and cook for 1 minute, stirring constantly.
Add the red lentils, vegetable broth, crushed tomatoes, and bay leaf. Stir to combine, bring to a boil, then reduce the heat to medium-low and simmer, partially covered, for 15–20 minutes, or until the lentils are tender.
Remove the bay leaf. Use an immersion blender to blend the soup to your desired consistency. I like mine quite blended and creamy, but still with a little texture. Stir in the lemon juice, taste, and adjust the salt and pepper if needed. Serve immediately.
Notes
Store leftovers in an airtight container in the fridge for up to 4–5 days. Add a splash of broth or water if the soup thickens.
Freeze cooled soup in an airtight container for up to 3 months, leaving a little space at the top.
Thaw overnight in the fridge, or reheat gently from frozen with a little broth or water.
Reheat on the stovetop over medium-low heat or in the microwave until hot, adding extra liquid if needed.