Chop your rhubarb into 1/4" pieces, zest and juice 1/2 orange.
In a medium saucepan put rhubarb, sugar, orange zest and juice, water, turn the heat on medium and bring to a boil.
Turn the heat to low and continue cooking, stirring once in a while, for 15 minutes until rhubarb softens and start to break up.
Remove from the heat and cool.
Preheat for waffle maker.
In a large bowl mix buckwheat flour, baking powder, baking soda and salt. Set aside.
Separate the egg whites from the egg yolks and whip the egg whites with sugar in a medium bowl on high speed until stiff peaks form, like if you are making a meringue. (The bowl you are using should be completely grease-free or the egg whites won't whip properly).
In a separate bowl mix together egg yolks, vanilla, yogurt, kefir or buttermilk, melted butter and water.
Add that mixture to the flour mixture and combine with a whisk.
Gently fold a half of whipped egg whites with a spatula into the waffle batter, then fold in the remaining half.
When your waffle maker is ready, lightly brush it with melted butter and scoop the batter into it. Cook according to manufacture's directions. Mine cooked 8 minutes each.
Scoop dollops of vanilla cream and rhubarb compote into a serving dish and swirl with a fork.
Serve waffles hot with a dollop of rhubarb cream.