Pre-heat a large wok or skillet over medium high heat and spray with cooking spray. Sprinkle chicken with salt and pepper and add to pan. Saute until brown, about 7-9 minutes; remove chicken from pan and set aside.
In the same hot skillet, add the asparagus and saute until bright green and crisp-tender, about 3-4 minutes.
While the asparagus is cooking, whisk together all remaining ingredients (coconut milk through curry paste) in a small bowl.
Add the chicken back to the hot pan and pour in the sauce. Use a wooden spoon to scrape up browned bits from the bottom of the pan. Bring mixture to a boil then reduce heat to low. Simmer curry for 7-9 minutes before serving over rice. Garnish with cilantro and scallions if you wish.