- Bring chicken broth to a boil in a saucepan.
- Add garlic, cinnamon, star anise, bird's eye chili, brown sugar, and rice vinegar. Reduce heat to medium and simmer for 15 minutes. Remove from heat; cover and keep warm.
- In the meantime, heat oil in a skillet over medium-high heat. Add beef and cook for 6 to 7 minutes on each side, or until the meat is cooked but still pink. Season with salt and pepper.
- Remove from heat; cover with aluminium foil and allow to sit for 5 to 10 minutes. Slice into thin strips.
- In a saucepan, cook rice noodles according to package instructions. Drain and divide evenly among 4 large soup bowls. Add bean sprouts and sliced beef. Pour broth over top. Garnish with daikon, cilantro, green onions, peanuts and lemon zest.
For a peanut-free version, replace with grilled soy beans sold as a snack.