Heat oil in a skillet sauté onion 1 minute. Add garlic and continue cooking until onion is tender but not golden. Add chopped tomatoes, cilantro sprigs and cumin. Cool for 5 minutes and blend. Season to taste.
Place mixture in a bowl and add water, wine and tomato paste.
Pour half mixture into a large pan and place fish fillets previously seasoned. Place peppers and ají on top of fish and cover with rest of mixture.
Cover pan and cook at low heat for 10 to 12 minutes or until fish is just cooked. Add potatoes, peas, parsley and chopped cilantro. Sprinkle with lemon juice. Bring to a boil and serve immediately.