I get email newsletters from a Japanese health food company called Yomeishu Seizo, and this month they did a feature on mandarins (mikan in Japanese), including some novel "cooking challenges." Namely, oven roasted mandarin and mandarin rice. The mandarin rice looked so easy that I had to try it!
You literally just put rice and water in your rice cooker as usual (I was my usual lazy self and didn't even rinse the rice), sit a peeled mikan on top of the rice, and press go (or whatever you usually do to make your rice cooker work).
By the time the rice is cooked the mikan gets soft enough that it's easy to break up and mix through.
The original post (here, in Japanese - scroll down to "Challenge 2" for their photos) suggests 2 cups of rice with 1 mikan, but I tried 1 cup with one mikan and the flavour was good. Subtler than I was expecting actually, but good.
So there's one super easy way to add some vitamin C to your dinner!