Method:

1. Cut the sirloin against the grain into slices a little less than a quarter of an inch thick.

2. Then, cut each slice into strips about half an inch wide. Place into a medium bowl.

3. Mix with the beef strips the  fish sauce, garlic, and lemongrass.

4. Divide the noodles between two bowls. Top with the julienned cucumber, pickled carrot and radish and finger chili (if using). 

5. Heat the peanut oil in a wok to smoking point. Stir-fry the beef for about two minutes.

6. Divide the beef between the two bowls.

7. Top with fresh herbs, peanuts, and fried shallots.

8. Serve.