Wash all of your jars and lids with soap and warm water.
Place jars in the oven on the bottom rack for 20 minutes or until completely dry. Boil lids in a small pot to sterilize them.
Making Canned Green Tomatoes Salad:
Wash all the vegetables. Using a sharp knife, cut each tomato in half, remove the stem part then cut tomatoes into 1/3"-thick slices. Place cut tomatoes in a large mixing bowl.
Grate carrots on the larger holes of the grater. Add grated carrots to the bowl of tomatoes.
Finally, peel and cut each onion in half, then in half again, then slice them into thick slices. Add sliced onions to the bowl with tomatoes and carrots. Don't slice the onion too thin or it will become too soft while cooking the salad.
Add 6 Tbsp of salt to the bowl with vegetables, mix them well, cover with plastic wrap and let the mixture sit for 12 hours at room temp. It's best to add salt in the evening so that in the morning you can drain the juice. Twelve hours later drain the juices from the vegetables.
In a large cooking pot, big enough to fit all the vegetables, mix together 1 cup of Canola oil, 1 1/4 cup of white vinegar and 1 cup of sugar until it dissolves. Add drained vegetables to the pot and mix them so they will be coated with the syrup. Finish by adding 5-6 peppercorns and 5 bay leaves. Cover and bring the pot to a boil and cook vegetables on med/high heat for 30 minutes, stirring 3-4 times in the process.
While vegetables are cooking, clean and sterilize your jars and lids.
When 30 minutes are up, remove vegetables from heat and add them to each jar while piping hot, leaving just 1/2" space at the rim. Pack the veggies in (you don't want air pockets). Screw the lids on enough to keep a tight seal in place but don't over-tighten them since air bubbles need to be able to escape.
Place packed cans into the canning pot and cover with 1-2 inches of water. Bring to a boil and process 15 minutes. Remove from the pot with jar lifter and leave at room temperature undisturbed for 12-24 hours. You may hear a pop when the jars fully seal. After 24 hours, check that the seal has formed by pushing down on the center of the lid - it should not move at all. If the seal does not form, refrigerate salad and enjoy within 3 months.