Broccoli Chowder

1 TBSP Olive oil
1 lg onion, chopped
1 lg carrot, diced
2 stalks celery, diced
1 lg potato, peeled & diced
2 cloves minced garlic
1 TBSP flour
1/2 tsp dry mustard powder
1/8 tsp cayenne pepper
28 oz chicken or veg broth
8 ouces broccoli, stems & florets seperated
1 cup shredded cheese
1/2 cup sour cream
1/8 tsp salt

Heat oil in a Dutch oven, over med-high heat. Add onion, carrot, & celery. Cook until soft. Add potato and garlic, cook 2 minutes. Stir in flour, mustard powder & cayenne pepper. Cook another 2 minutes. Add broth & broccoli stems; bring to a boil. Cover, reduce to med. Simmer for 10 minutes. Stir in florets; simmer covered until tender (10 minutes). Mash 2 cups of chowder, return to pot. Stire in cheese & sour cream, cook over to med until cheese is melted & heated through.