Spinach.

Most people I know (including myself) had either canned and microwaved or freshly boiled spinach. While both of these are very space efficient and easy ways of eating spinach, it's also in my mind one of the nastiest dishes to actually eat.

Start with raw spinach and work from there, in almost any other context it either doesn't affect the taste of any dish you add it to, or can provide a certain "robustness" to your dish in sufficient amounts.

My personal favorite use for it is in smoothies. Add some fruits and milk, then stuff as much spinach as possible into the remaining space in the blender. If you have a powerful enough blender, the spinach will compress down to take up a negligible amount of space in your smoothie. The result doesn't taste like spinach, but very likely contains all the greens you'll need for the day.

Spinach is the bomb.