Buy large amounts on sale; then saute and store seasoning veggies (garlic, onion, peppers, celery) for quick and easy starts to meals.
I start all meals with basics- garlic, onion, peppers & mushrooms. Buy bunches on sale, cut them up, saute in batches of different mixes (gar + oni; onion + peps, all 4, just 1) and freeze in amounts needed to start a dish. When needed pull out & toss in a pan. Saves lots of time cutting.