Sprinkle chicken pieces with salt and pepper.

Place flour on a plate and roll chicken pieces in it to coat; shake off excess flour.

Heat oil in a Dutch oven or large, deep skillet over medium-high heat.

Add chicken pieces and cook, turning occasionally until golden brown, about 10 minutes.

Transfer chicken to a bowl.

Meanwhile, trim celery, saving any tender leaves for garnish. Use a vegetable peeler to remove any tough strings.

Cut celery into 3-inch pieces.

Lower heat to medium and add celery and potatoes to the pan.

Cook, stirring frequently until celery softens, about 5 minutes.

Stir in wine and cook, scraping up any browned bits from the bottom of the pan until most of the liquid has evaporated.

Pour in broth and stir in mustard.

Return chicken to the pan, bring to a boil and then lower heat; cover the pan and simmer until chicken is cooked through and very tender, 20 to 25 minutes.

With a slotted spoon, transfer chicken and vegetables to a large serving bowl.

Return the pot to the stove and cook over medium heat until sauce is thickened, about 5 to 6 minutes.

Whisk in yogurt, taste sauce and add more salt and pepper if desired, and pour over chicken.

Use a vegetable peeler to remove any tough strings.