Heat oil in a large non-stick fry pan over medium heat. Add onion. Cook stirring until softened.
Add beef and cook until just browned. Add curry paste. Cook for 1 minute until fragrant. Add coconut milk and brown sugar. Bring to a simmer. Reduce heat to low and cook for 5 minutes. Add vegetables and cook for a further 4-5 minutes.
Serve on steamed rice sprinkled with coriander leaves.