You can find them in the spice isle, they are very common.
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onion flakes = dried minced onion = dehydrated onion flakes Notes: These are onions that have been chopped and then dehydrated. They lack much of the pungency of fresh onions, but they're convenient and great for backpacking. Equivalents: 1 small onion = 1/3 cup = 1 teaspoon onion powder = 1 tablespoon dried onion flakes Substitutes: onion powder (1 teaspoon onion powder = 1 tablespoon dried onion flakes) OR onion (1/3 cup chopped fresh onion = 1 tablespoon dried onion flakes) web page