Slice the chorizo into 1/4 inch slices
Add the chroizo to a cold medium pot
Turn the heat to medium and saute the chroizo for 5 minutes to render some of the fat
Add optional chopped onion if using
Slice the garlic and add it to the pot. Saute for 30 seconds
Add the diced tomatoes, tomato sauce and chicken stock
Add optional kale and roasted red pepper if using
Simmer for 10 minutes
Add the shrimp and simmer until the shrimp turns pink and curls up, about 5 minutes
Season with salt, pepper and red chili flakes to taste