In a large skillet heat oil to medium heat. Season chicken drumsticks with salt and pepper, add them to skillet and cook over moderately high heat, turning, until golden brown all over, about 10 minutes.
Add onion and cook, stirring occasionally, until softened, about 3 minutes.
Add garlic and cook for 1 minute.
Add broth, coriander and basil and bring to a boil.
Cover and cook over moderately low heat until the chicken is cooked through, about 20 minutes.
Transfer chicken to a platter, cover with foil to keep warm.
In a small bowl, whisk mustard, sour cream, tarragon and capers.
Whisk mixture into the skillet and simmer sauce over moderate heat until thickened, about 5 minutes.
Adjust seasonings, if desired.
Return chicken to skillet, heat and turn to coat.
Serve with crusty bread.
Tips
Recipe can be made ahead and be refrigerated for up to 2 days.