Brush the corn liberally with olive oil and season well with salt and pepper. Grill, turning every few minutes, until light gold all over and cooked, about 12 minutes. Let cool and cut off the kernels. Discard the cobs.
the tomatoes and cut a small X on the bottom of each. Brush with olive oil, season with salt and pepper, and place on the grill, X side down, away from direct heat. Cover the grill
and cook until the tomatoes begin to soften but are not cooked all the way through (or they will melt
through the grate
!), about 15 minutes. Set aside until cool enough to handle, then peel
. Cut the tomatoes in half crosswise and squeeze out the juice and the seeds through a sieve
into a bowl. Reserve the juices and chop
Put the onions
in the non-reactive medium bowl and toss with 2 tablespoons of the vinegar. Let marinate until the color changes, about 10 minutes.
Add the chopped tomatoes, reserved tomato juice, onions, basil, and 1/3 cup olive oil to the corn
. Toss well. Taste for seasoning and adjust with salt, pepper, and remaining vinegar. The salsa
is best eaten the same day but will keep, covered and refrigerated, a day or so.
Serve with tortilla chips
or as a topping for tacos