It’s important to always wash and rinse your tomato before you cut it. This will remove any dirt and pesticides that may be on the skin of the tomato. You can use a paper towel and a bowl of water to do this.
A way you could slice your tomatoes is by using a finger guard to hold the tomato in place while you cut. You can also use a cutting board or just the palm of your hand if you have an extra set of hands to help hold it in place.
After you have washed, rinsed, and sliced your tomatoes, it’s important to always wash your knife so you don’t spread any bacteria from one tomato to another.
So this is how you can dice a tomato.