Pre-heat the oven to 350°F and lightly grease a casserole dish.
Heat the oil in a frying pan over a medium heat.
Put in the burgers and brown them on both sides, about 5 minutes in total, then place them on a plate.
Press the garlic on to both sides of the burgers, and place them in the casserole dish.
Add the olives and the rest of the ingredients, apart from the sour cream, to the frying pan.
Stir over a medium heat for 3-5 minutes.
Pour .this sauce over the burgers and bake, uncovered, for 45 minutes.
Remove from the oven.
Pour the sour cream over the burgers.
Cover the casserole and leave for 5 minutes.