Here is my guide to picking the best tomatoes.
Look for tomatoes that are grown locally, the closer the better. If not local, tomatoes are often picked green and ripened off the vine, producing fruit that has not properly or fully developed its flavor. The best tomatoes are in season, and usually the farmers’ markets carry these. I also look for tomatoes that have stems attached, which allow them to retain their flavor and stay fresh. The stem and leaves of the tomato should be green and tightly attached. Brownish, loose leaves or stems indicate that the tomato has been sitting around for a while. The tomato shouldn’t have any soft spots.
Buy tomatoes no more than a day or two before you plan to use them. This will ensure the best flavor and texture, providing the vendor has treated the tomato properly. When you shop, pick your tomatoes from the top of the pile, staying away from high tomato piles, because the bottom ones get bruised.
When you buy a tomato that is underripened, let it ripen in a cool place, such as the windowsill. Simply putting them in a brown bag or just resting on your counter also works well.