In a stock pot on medium melt butter. Add in flour and stir well.
Mixture will start to bubble.
Continue cooking until French Roux resembles a caffe latte color. Stir consistently during this stage of cooking.
Once the desired color is reached. Add in the bell pepper, onions, celery. garlic and stir well. Cook for 2-3 minutes.
Add in shrimp stock and tomatoes. Cook for 10 minutes.
Add in the sweet potatoes, corn, spices and cook for 15 minutes.
Add in the crawfish tails, sausage and cook for 5 minutes. Taste and adjust for your flavor palette. Pour in evaporated milk and reduce to a low heat. Simmer for 15 minutes.