Step 1: For the fish:
Rinse fish and pat dry with paper towels. Pour lemon juice over fish, sprinkle with salt and pepper. Heat your vegetable oil and when hot start dredging your fish with the flour and immediately start to fry (at this time lower the heat) slowly until golden on both sides and fish is cooked. Drain on paper towels.
Step 2: For the Escabeche:
Heat your olive oil and add garlic and onions until they sweat a bit; add peppers, peppercorns, bay leaves and cook on very low flame until vegetables wilt, but do not lose their color. Take off flame and add the rest of the ingredients and let cool. Put some of the Escabeche mixture on bottom of a large deep glass or plastic receptacle and then place fish on top. Repeat layering until all the pieces of fish are covered with the mixture. Cover and refrigerate for 24 hours so fish absorbs the liquids.