Start a large pot of water (deep enough to submerge a whole duck) on the stove, bringing it to a rolling boil.

Remove giblets and neck from the duck cavity. Trim any excess fat from body cavity and neck. Save giblets and neck for making stock. Put the duck in the pot of boiling water and boil for 10 minutes. This will help render out some of the fat. Remove the duck and let cool. Pat dry.

With a very sharp paring knife, prick the duck skin to help release the fat, especially where the skin is thickest being careful not to pierce the meat. It can be helpful to hold the knife nearly parallel to the bird. After piercing the skin, use the knife blade to score the duck in a crosshatch pattern (making deep cuts into the skin only, and not into the breast meat). Flip the bird and score the back as well. Then, pat dry thoroughly.

Season the duck all over including its cavity with salt and pepper. In a small bowl combine garlic, chopped herbs, citrus zest, coriander and garam masala. Make a paste. Rub garlic paste all over duck, inside and out. Place the duck, breast side up on a rack in a roasting pan and stuff the cavity with herb springs. Refrigerate uncovered for 4 - 24 hours.

Preheat the oven to 450F. Roast for the duck for 30 minutes. Remove the pan from the oven and carefully prick the skin over the top of the duck with a sharp paring knife to release fat. Reduce the oven temperature to 350F and continue roasting until the skin is golden brown and the internal temperature at the thickest part of the thigh reads 165F on an instant-read thermometer at about 1 hour to 1 hour 30 minutes longer. Remove the duck from the oven and transfer it to a cutting board to rest for 15 minutes. Next, carve and serve.