Combine onion with 2 teaspoons salt in non-reactive bowl. Allow to stand at least 1 hour but not more than 1 1/2 hours. Onion will wilt slightly, throw off some juice and become much less pungent. Drain juice from onion, rinse with cold water and drain again. Peel peaches and chop medium-fine with knife. Do not use food processor. Combine peaches in non-reactive bowl with onion, vinegar, jalapeno and remaining salt. Finely mince basil and stir in. Serve at once. Makes 2 cups, s, 6 to 8 servings.