Sundried tomatoes are available either dry, or marinated in oil and herbs.
Marinated tomatoes are moist and tender. They are ready to use, and have a deeper, more complex flavor which the marinade imparts.
Dried tomatoes must be reconstituted. You can soak them in cold water overnight, or in boiling water for 10-15 minutes. The flavor of dried tomatoes is unseasoned and sweet, with an intense, concentrated tomato flavor, similar to tomato paste.
Sun dried tomatoes are easy to replicate at home in the oven (so technically they are “oven-dried”). Halve fresh tomatoes, sprinkle with salt, and place cut-side up on cake racks. Place in a 200˚F oven and cook slowly 6-12 hours. Check the frequently. Finished tomatoes should be flexible, not brittle. Larger tomatoes take longer. If they are too close together it will take longer. If you use a baking sheet rather than a rack it will take longer, too, but it will eventually work. When they are done, cool completely and store air tight.
You can also make your own authentic sun dried tomatoes. Halve fresh tomatoes, sprinkle with salt, and place cut-side up on raised screens. Set them in the sun for 1-4 weeks (depending on where you are and how hot it is). Be sure to bring them in at night to prevent dew from forming (and critters from snacking).
Marinate dry tomatoes yourself. Combine 1/2 cup each of good olive oil and balsamic vinegar with 2-3 crushed cloves of garlic, and 1/2 teaspoon each of dried tarragon, basil, oregano, and crushed fennel seeds. Plump dry tomatoes in boiling water, drain, cover with marinade, and set aside to marinate at least 8-hours. Refrigerate for storage longer than 2 days. You can also store at room temperature in sterilized jars.