In a large pot, heat olive oil and sauté onions until translucent. Add in garlic and cook for 1 minute.
Add in chopped carrots and celery and cook for 5 minutes, stirring occasionally.
Pour the mashed tomatoes and green lentils over the vegetables. Sprinkle salt, cumin, black pepper and paprika over these. Cook for 2-3 minutes, stirring occasionally.
Add in water and lemon juice and bring it to a boil.
Reduce the heat to medium low and cook until lentils are tender, about 20 minutes.
Add in black beans and cook for another 5 minutes. Remove from heat.
Garnish with chopped parsley and serve.
NOTES
You don’t need to soak uncooked green lentils before cooking. You can add them right into the pot and start cooking.
If you want to use cooked lentils, make sure not to overcook them. You can add them at the same time with black beans. Make sure to drain and rinse first.
You can substitute vegetable broth for water to give the soup more flavor.
To store any leftovers, you can simply place the black bean and lentil soup inside of an airtight container. Then, place the container in the fridge for about 4 days.
You can freeze the soup for a couple of months. When freezing soup, you can even place them in re-sealable plastic bags so that they can be frozen on a flat surface. This will make storing them much easier. To thaw the soup, place the entire container in the fridge and allow the soup to defrost overnight. You can also defrost the soup in a microwave on a low heat setting or in a pot over low heat.