Heat the oil in a medium saucepan over medium heat. Add the onion and garlic, saute 5 minutes or until translucent.
Add the rice and stir to coat. Add the stock, salt, and pepper and bring to a boil. Lower the heat and simmer, covered, for 45 minutes or until all liquid is absorbed. Remove from heat and let pan stand, covered, for 5 to 10 minutes.
Using a fork, fluff the rice and toss in the feta, mint, and orange zest just to combine. Serve hot or at room temperature.