Curried Shrimp

For the rice pilaf:
1 Tbs. unsalted butter
1/2 cup finely diced yellow onion
2 cups long grain white rice
3 cups chicken stock, homemade or low-sodium
1 sprig thyme
1/2 bay leaf
1 tsp. kosher salt
1/4 tsp. freshly ground white pepper

For the curry:
4 Tbs. unsalted butter
1 cup diced onion
1/2 cup finely diced leeks
1/2 cup finely diced carrots
1/2 cup finely diced celery
1 Tbs. minced garlic
2 Tbs. Pataks curry paste (available at Harris Teeter)
2 Tbs. hot Madras curry powder
2 cups chicken stock, homemade or
    low-sodium
1/4 cup store-bought mango chutney
1 banana, peeled and mashed
1/2 cup diced Granny Smith apple
1/2 cup coconut milk
1 1/2 lbs. large (21/25 count) local shrimp (preferably white), peeled and deveined