Lightly bruise half of the peppercorns in a mortar and pestle. Remove and transfer to a large mixing bowl. Add 1 tablespoon garlic, 2 teaspoons salt, 1 teaspoon sugar, and then add the chicken. Mix and coat the chicken pieces well. Cover and marinate in the refrigerator for 1 hour.
Bring a large pot to high heat and add the oil, remaining garlic, remaining peppercorns, and fry until fragrant. Now add the marinated chicken and sear both sides until slightly browned. Add the tomatoes, carrots, and annatto oil. Stir to combine, and then add the red shallots, onion, coconut juice, fish sauce, and remaining sugar and salt.
Bring the mixture to the boil and skim off and discard any impurities that rise to the surface. Turn the heat to medium-low and allow to simmer for 40 minutes uncovered.
Transfer to a deep bowl, garnish with peppercorns and serve with crisp baguette.