Put a cast-iron ridged grill pan over high heat and let it get really hot (about 10 minutes). Cut the beef into long, thin strips and season with the pepper and sesame oil. Lay the beef strips in the pan and do not touch them until they start to smoke. Then turn them over and leave to cook a minute longer.
Combine the sugar and fish sauce in a mixing bowl. Transfer the beef into the mixture and toss well (the fish sauce works in place of salt and gives great flavor). Let cool.
To make the dressing, heat the vinegar in a pan. Remove from the heat and add the chiles, sugar, garlic, and warm water, then the fish sauce, lime juice, and carrot julienne.
Put the rice vermicelli in a large bowl. Pour the sauce over it and let soak until the vermicelli is soft. Drop in the shallots, garlic, herbs, and yard-long beans, then add the beef and mix together. Sprinkle with the chopped peanuts, toss, and serve.