Prepare the Tomatoes and Jars

• Prep the tomatoes. Wash the Roma tomatoes well. Using a clean chopstick or skewer, gently poke a small hole where the stem was attached. This can help the tomatoes absorb the brine and may help reduce splitting.
• Prep the dill. Rinse the pickling dill well. Cut the dill florets and stalks into smaller pieces so they're easy to divide between the jars.
• Prepare the jars. Wash the jars and lids thoroughly. To sterilize the jars, place the jars upright in a large pot and cover them with water by at least 1 inch. Bring to a boil and boil for 10 minutes, adjusting for elevation as needed. Keep the jars hot until you're ready to fill them. Prepare the lids according to the manufacturer's directions.

Fill the Jars

• Add the seasonings. Divide the dill florets and stalks among the jars. Add the sliced garlic and 1 teaspoon pickling spice to each jar.
• Add the onion and tomatoes. Divide the sliced onion among the jars, then gently pack in the tomatoes. I was able to fit about 4–5 Roma tomatoes per 32-ounce jar, depending on their size.
• Add boiling water. Carefully pour plain boiling water over the tomatoes. Let the jars stand for 15 minutes.

Make the Pickling Brine

• Prepare the brine. Add the vinegar, water, pickling salt, and sugar to a large pot. Stir and bring the mixture to a boil.
• Drain the jars. After the tomatoes have rested for 15 minutes, carefully pour the plain water out of each jar. You can hold a small strainer over the opening to catch any dill, garlic, onion, or pickling spices that try to escape. Return anything you catch to the jar.
• Add the hot brine. Carefully pour the hot pickling brine into each jar, making sure the tomatoes are completely covered.
• Remove air bubbles. Slide a chopstick or plastic utensil around the inside of each jar to release trapped air bubbles. Gently tap the jars if needed.
• Wipe the rims: Using a clean, damp paper towel, wipe the rim of each jar to remove any brine or food residue. 
• Close the jars.  Center a clean lid on each jar, add the ring, and screw it on until snug.

Pickling Tomatoes

• Water-bath the jars: Place the filled jars upright in a water-bath canner with a rack and cover with at least 1 inch of water. Bring to a full boil and simmer on medium/low for 15–20 minutes. Carefully remove the jars with a jar lifter and place upright on a towel. Covers the jars with a blanket and leaves them undisturbed for 24 hours to cool.
• After transfer them to a cool dark place or refrigerator.
• For the best flavor, let the tomatoes marinate for at least one week before opening, the longer they sit, the more delicious that garlicky, dill pickle flavor becomes! Enjoy!