Pre-heat your oven to 450°.
Rub the outside of your chicken with some olive oil and sprinkle liberally with salt.
Place the chicken into the middle of a roasting pan, and place in the oven for 15 minutes. Then, turn the heat down to 350°. The cooking time on the vertical roaster is 15 minutes per pound total. *
While the chicken is roasting, cut your kumquats in half and toss them with the quartered onion and the rosemary sprigs and about 2 tablespoons of olive oil. Sprinkle the mixture with salt.
Add the kumquats mixture to the bottom of the roasting pan when the chicken is about 20 - 25 minutes away from being done. **
Remove the chicken from the oven, place on a cutting board and let sit for a few minutes before removing from the vertical roaster. Cut and serve.