Winter is kind of a grim time for produce---root vegetable, root vegetable, bitter greens, root vegetable---so I find myself turning again and again to citrus to brighten things up a bit. A couple of years ago, I bought a few oranges at Whole Foods. I got them home, cut into one, and recoiled: it was a deep coral, almost pink color inside.
Some googling informed me that I had inadvertently purchased Cara Cara oranges, and every year since then I have anxiously looked forward to the brief time when they're in season.
In addition to being gorgeous, they're lower in acid than other oranges, and very very sweet, with almost floral flavor. They're super delicious, and give my other winter citrus boyfriend -- the minneola tangelo -- a run for its money.
I've only ever seen them at Whole Foods (at absolutely extortionate costs, it must be admitted- $2 a pound or more) but I'm sure they must also be sold elsewhere- keep an eye out!