Ingredients

1/4 cup canola oil 

1 pound shrimp shells (from 10 pounds shrimp) 

1 onion, coarsely chopped 

1 rib celery, coarsely chopped 

1 carrot, chopped 

1 leek, white part only, chopped 

4 cloves garlic, crushed 

1 bay leaf 

1 sprig fresh thyme 

Preparation

Heat oil in a large saucepan over high heat. Add shrimp shells and cook, stirring frequently, until toasted, about 10 minutes.

Add onion, celery, carrot, leek, and garlic and cook for 3 minutes. Add 12 cups water, bay leaf, and thyme; bring to a boil. Reduce heat to medium and cook until reduced by half.

Strain stock, discarding solids; let cool to room temperature. Stock may be used immediately or transferred to an airtight container and kept refrigerated for up to 3 days or frozen for up to 3 months.