Because of the olive oil, these don’t have as long a shelf life as plain dried tomatoes, but that doesn’t matter, since they’ll get eaten pretty quickly. They are delicious!
Put your olive oil, herbs, and salt in a large bowl, and stir to mix.
Wash and slice your tomatoes about 1/4 inch thick. Discard most seeds and extra water. Cut out stem areas and any ugly spots.

Put the tomatoes in the bowl containing the oil and herbs, and gently mix them well, to get them all covered with oil and herbs. I usually do this with my hands.
Gently place your tomato slices on your dehydrator shelves, making sure they don't overlap or actually touch each other. You want the air to circulate around them. Put the shelves in the dehydrator and turn it on with the temperature set to about 105-110F (40-44C). After a few hours you will need to turn them over. I usually do that at least twice, to make sure they dry evenly. When they are leathery and tough (not pulpy at all), take them out. They will be a little oily, but they shouldn't be fleshy. Freeze them for a couple of days in a ziplock bag or some other container, to kill any possible insect eggs. I store them in my refrigerator or in a jar right on my countertop, since I eat them often.