To prepare paste, combine first 6 ingredients in a blender; process until smooth. Spoon into a bowl.
To prepare stew, heat a Dutch oven coated with cooking spray over medium-high heat. Add beef; cook 5 minutes, browning on all sides. Remove from pan.
Reduce heat to low; add oil to pan. Add paste; cook 2 minutes, stirring frequently. Add curry, cinnamon, and bay leaf; cook 30 seconds, stirring constantly. Stir in beef, soy sauce, and broth. Increase heat to medium-high. Bring to a boil; cover, reduce heat, and simmer 1 hour.
Add sweet potato, carrot, celery, and mushrooms. Bring to a boil; cover, reduce heat, and simmer 50 minutes or until beef and vegetables are tender. Remove from heat; stir in coconut milk. Discard cinnamon stick and bay leaf.