Blend shallots (or onion), garlic, and ginger with ¼ cup (60ml) water. Transfer to a bowl. Add curry and chili powder. Mix to form a paste.
Preheat oven to 375°F (190°C).
Place chicken pieces in a large bowl. Add 2/3 of the spice paste. Stir to coat chicken. Combine remaining 1/3 spice paste with potatoes. Stir to coat.
Transfer chicken and potatoes to a shallow baking dish. Drizzle vegetable oil over the chicken and potatoes.
Roast in the oven for 1 hour 15 minutes to 1 hour 30 minutes until chicken is fully cooked.
Remove and serve immediately with steamed basmati rice.