Don't Add Garlic at the Same Time as Onions — Garlic Burns in Seconds

Onions are dense and high in water — they need 5-8 minutes over medium heat to soften and turn translucent. Garlic is thin, dry, and full of sugars that caramelize almost immediately. Put them in together and the garlic will be black and bitter long before the onions are ready.

Always add garlic in the last 30-60 seconds of cooking the onions, when they're nearly done. Stir constantly and watch for the garlic to become fragrant — that's when it's done. One minute of inattention turns the whole dish bitter.