Heat 2 tablespoons olive oil in a very large heavy skillet over medium high heat. Once hot, add the tomatoes, making sure there is space around each tomato (they are not touching) and the pan is not crowded. If you’re using a medium pan, cook the tomatoes in 2 batches, 1 pint at a time. If the pan is too crowded, the tomatoes will steam instead of blistering.
Cook for 1 minute without touching the pan, then 2 to 3 more minutes until blistered, shaking the pan several times to rotate the tomatoes.
Turn off the heat and drizzle with the balsamic vinegar, gently shaking several times to coat. Add 2 pinches kosher salt and fresh ground black pepper to taste. Serve warm, in pasta or over grilled fish.