Bring the stock to a boil. Skim and discard the scum. Add the fat to the pot and bring to a boil. Add the tomatoes, onions, and garlic; turn the heat down to a simmer. Simmer 20 to 30 minutes, until the onions are soft.

Puree with an immersion blender or pour contents into standing blender and secure lid. Working in batches, puree the soup

For Blendtec: Use Medium Speed or Speed 6 for 30 seconds.

For Vitamix: Start on VARIABLE Speed 1, turn machine on and slowly increase to Speed 10/HIGH. Blend for 45 seconds.

Add the ground sausage and simmer another 10 minutes. Add salt to taste. Add fresh basil as garnish in Stage 2.

Sauté the sausage in the fat until it’s nicely browned, about 15 minutes. Remove to a plate. Add the onions to the pan and sauté until translucent. Add the garlic and stir for another minute. Transfer onions and garlic to a soup pot. Add the stock to the pot. Bring to a boil, skim, and discard the scum. Add the tomatoes and simmer 15 minutes. Remove from the heat and let cool slightly.

Puree with an immersion blender or pour contents into standing blender and secure lid. Working in batches, puree the soup

For Blendtec: Use Medium Speed or Speed 6 for 30 seconds.

For Vitamix: Start on VARIABLE Speed 1, turn machine on and slowly increase to Speed 10/HIGH. Blend for 45 seconds.

Transfer pureed soup back to the soup pot. Add the sausage and stir to incorporate. Let the ingredients simmer together for another 15 minutes. Season with sea salt to taste. Sprinkle with fresh chopped basil to garnish and serve.