Mince the garlic.

Heat vegetable oil in a heavy saucepan over medium-low heat.

Add minced garlic and cook until fragrant (about 30 seconds).

Add curry powder and cook for 30 seconds, stirring constantly.

Stir in chicken broth, coconut milk, water, minced lemongrass, gingerroot slices, and black peppercorns.

Bring the mixture to a boil.

Add the whole chicken breast.

Reduce heat to a bare simmer and poach the chicken for 20 minutes, or until cooked through.

Transfer the cooked chicken to a bowl and let it cool.

Keep the poaching mixture warm.

While the chicken is cooling, soak the rice noodles in warm water for 5 minutes to soften.

Drain the softened noodles.

Cook the drained noodles in a large saucepan of salted boiling water for 5 minutes.

Drain the cooked noodles in a colander.

Rinse the noodles under cold water and drain well.

Discard the skin and bones from the cooled chicken.

Shred the chicken meat.

Stir the shredded chicken into the warm poaching mixture.

Add lime juice and fish sauce to the soup.

Cook the soup over medium heat until heated through.

Divide the cooked noodles among 6 to 8 bowls.

Ladle the hot soup over the noodles in each bowl.

Sprinkle chopped fresh coriander over the soup.

Drizzle chili oil over the soup to taste.