Cook shrimp with bay leaves in boiling water until just pink.
Discard bay leaves.
For sauce: Melt butter in large skillet over medium heat.
Add onion, apples, banana, chutney and curry powder.
Season with ground red pepper to taste.
Cook 3 minutes, stirring constantly.
Add stock and bring to boil.
Reduce heat and simmer 2 minutes.
Season with herb salt to taste.
Transfer mixture to blender or processor (in batches if necessary) and puree.
Return sauce to skillet, place over medium heat and simmer 5 minutes.
Sauce can be refrigerated 1 to 2 days.