Write SQL query to solve given problem: Provide the order ID of Frank Olsen of the South region.. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT T1.`Order ID` FROM south_superstore AS T1 INNER JOIN people AS T2 ON T1.`Customer ID` = T2.`Customer ID` WHERE T2.Region = 'South' AND T2.`Customer Name` = 'Frank Olsen'