In a skillet, heat oil over medium heat. Sauté onion, ginger and curry powder until onion has softened, about 5 min. Add peaches, sugar and salt; cook until peaches break down, about 5 min. Remove from heat and let cool.
Using an immersion blender, purée peach mixture. Add yogourt and lime juice; stir to blend, adding about 2 tbsp (30mL) water (if desired) to achieve runnier consistency.
Preheat grill to medium-high. Brush all but 1/4 cup (60 mL) peach sauce on chicken thighs. Place chicken on greased grill; close lid and grill until chicken is cooked through, about 4 min. per side, basting twice with remaining peach sauce.
Dilute the peach sauce with a few tablespoons soy sauce and cider vinegar to create a flavourful curried salad dressing – perfect for quinoa salads or rice pilafs.