First, grab a small, sharp paring knife. A dull blade will just squish the poor tomato. And no one wants a squished tomato.
Look straight down at the stem end. You’ll see a little bullseye where the stem meets the fruit. Insert your knife at a 45-degree angle right next to that stem.
Now, repeat that cut on the opposite side. You’re making a tiny “V” shape. You should just be cutting into that white core, not the whole top half of the tomato.
Pop that little triangle out with your fingers. Voilà. You’ve removed the core. It took less time than scrolling past three cat videos. Probably.