Dissolve the salt in enough water to cover the banana pieces. Soak them in the salt water for 10-15 minutes to draw out the "pucker quality" of the unripe fruit.
Meanwhile, wash the shrimp in cold, running water, but don't shell or remove heads. Cook in 2 cups of boiling, salted water for 6-8 minutes. then peel off shells and remove heads. Save heads and cooking water.
In a large, heavy skillet or stew pot, saute the onion in oil over moderate heat until golden. Stir in garlic, tomatoes and pepper. Add shrimps.
(picture : google image)