Heat olive oil in a 10-12 inch stainless steel braising pan, or skillet. Saute the onion over medium heat for about 5 minutes until translucent. Add garlic and continue to sauté for another minute. Add the stock, chopped tomatoes, and lemon juice. Bring to a simmer on high heat. Once it starts to simmer reduce heat to medium and simmer for about 5 minutes. Add herbs, olives and cod fillets; cover and simmer for about 10 minutes, depending on how thick the fish is. Season with sea salt, chili flakes and pepper to taste. Serve cod mixed with tomato herb sauce over freshly steamed rice. Serves 4.