I was quite surprised, when buying seeds for my garden (I need heat tolerant varieties of everything) that some of the ones that were heat tolerant were also cold tolerant, either old varieties or sturdy hybrids.

Green Magic Broccoli is awesome, and there are lettuces like that. And while our unusual double tap freeze this year wiped out most of my garden, the fennel, which is heat tolerant in my experience, just did not freeze. All those little hairy leaves were completely undamaged. I did not expect that!