I've always loved the combination of tomato and orange. One of my go-to sauces for cheese ravioli is a simple reduction of tomatoes and orange juice, emulsified with fruity olive oil. The sweet and acidic fruits bring out the milkiness in the ricotta.
Although tomatoes and oranges are available year round, their seasons aren't concurrent. In the Northeast, the only fresh tomatoes worth eating in the winter are the small sweet cherry and grape varieties. This year, I've been enjoying baby Romas; indulging in their rich, concentrated tomato flavor. It didn't escape my notice that they are the same size and shape as kumquats and I'd feel remiss if I let citrus season pass without bringing the two together in a sweet preparation.
Cilantro and coriander, which taste to me of orange, adds herbal brightness and warm spice.