In a medium to large stock pot over medium high heat, cook the chorizo until crispy. Remove the chorizo and add the peppers, onions, carrots, and celery. Cook about 15 minutes, reducing the heat to low, until they soften and become aromatic. Add the garlic.
Season with salt and pepper. Add the butter and let it melt.
Whisk in the flour and cook for five minutes.
Add the clams and clam juice, making sure to whisk vigorously to get rid of any flour clumps. Let this simmer for ten minutes.
In the meantime, cook the sweet potatoes separately while the chowder simmers.
When the potatoes cook, drain and add to chowder. Cooking the sweet potatoes separately prevents them from turning mushy. This is also the moment you add back your chorizo, saving a tablespoon to sprinkle over the top of the chowder once served.
Once ready to serve, add half and half and let heat through for five more minutes. Taste and adjust seasoning.