Heat the oil in a large stockpot or dutch oven. Add onions and garlic, and saute until fragrant, about 3 minutes. Add the celery, carrot, potato, and mushrooms and saute for about 5 minutes until everything softens slightly. Season with salt, pepper, and spices and cook, about 2 minutes.
Add lentils and saute 1 - 2 minutes, then add the broth, water, and tomato paste. Stir to combine and until the tomato paste has dissolved. Bring the soup to a boil, cover, and reduce to simmer for 30 minutes.
Remove from heat and stir in almond milk, lemon juice, and spinach, and stir until the spinach has wilted. Serve immediately and top with your desired toppings.
For garnishes, I like to do a dollop of coconut yogurt, some fresh parsley, pepper flakes, cracked pepper and jalapeno slices. A little spicy, a little creamy and so good!