Thanks to their high water content, sweet onions are inherently crisp and juicy, and ice does a lovely job of keeping them that way.

1 large or 2 medium-sized sweet onions
1/2 cup seasoned rice vinegar (or rice vinegar plus 1 teaspoon sugar)
1 tablespoon chopped fresh basil
1/8 teaspoon dried crushed red pepper flakes
1 cup small ice cubes or coarsely crushed ice
Salt

Cut the onion(s) crosswise into 1/4-inch thick slices; separate into rings.
In a bowl, combine the onion rings, vinegar, basil, chile flakes, and ice; cover and chill 10 to 15 minutes, stirring occasionally. The ice will begin
to melt, diluting the vinegar to an appropriate level. Serve, adding salt to taste.

Yields 6 servings (as a side dish).