In a large frying pan, heat a couple tablespoons of olive oil.
Saute the garlic and onion until soft.
Add the rings and saute for about 3 minutes, stirring frequently.
Add the herbs, stock, tomatoes, tomato paste, olives, cayenne, and salt and pepper.
Cover with a lid and simmer on medium heat for 30 minutes.
Remove from heat, pour into dish, sprinkle with feta and serve.