Clean and dry your vegetables.
Cut them into similar sizes if you plan on roasting them. Alternatively you can just take turns with the varying sized pieces. If you're going to grill the vegetables we like to cut them in strips. My family likes the pieces of zucchini to be about 1/2 inch thick I feel like that makes it so they don't over cook to mush too quickly but everyone differs on preferences so be sure to play with it and see what you like.
Place in a food safe zipper bag. Alternatively you can stick it in a glass or plastic storage dish and shake it!
Pour in olive oil. I use about 1/4 C whether I'm using a handful of veggies or a whole gallon bag. If it doesn't seem to coat your veggies well you can use more. Not all of the oil will go into the food so don't worry about it being "too much"
Shake in the garlic salt. If you are using more than 2 cups of veggies I'd add in addition shakes depending on your families preferences. Remember that a lot of the seasoning will be left in the bag once you remove the veggies.
Seal the bag and massage to distribute the olive oil and seasoning.
Allow to marinate for an hour or up to 12 hours. Yes I have in a pinch just marinated for 30 minutes and when someone invited me out to dinner last minute I've saved my bag longer than 24 hours but I think it's best between 1 and 12 hours personally. But like I said this recipe is SO flexible and forgiving!
To cook just grill, sautée, roast in the oven, or air fry, making sure to flip according to your personal tenderness preferences. I like to use tongs or chop sticks to lift the vegetables out of the bag. Don't pour them out, you don't want the excess oil. On a hot grill or hot oven/air fryer (set at 400 F) it takes about 7 minutes.