In a large pot pour enough olive/vegetable oil to cover bottom of pot. Add onion, garlic and chicken and saute, turning chicken pieces, until chicken is 1/2 cooked (4 to 5 minutes).
Add 1/2 jar of olives along with 1/2 of the brine from the jar. Add the potatoes and enough water to cover chicken and potatoes. Cover and simmer over medium heat until chicken and potatoes are cooked and tender.