Bring water to a simmer in a medium saucepan over medium-high heat. Add 1 cup sugar and rhubarb, stirring to dissolve the sugar. Bring the mixture back to a simmer, bubble for 1 minute, then take off the heat. Cover and let sit for 1 hour. Using a slotted spoon, transfer the poached rhubarb to a small bowl. Return the remaining syrup to medium heat, bring to a boil, and cook until the mixture thickens to the consistency of maple syrup ( about 9 to 10 minutes). If not using immediately, store both the poached rhubarb and rhubarb syrup in the refrigerator.

While the rhubarb is resting, prepare the waffle batter. Add flour, baking soda, sea salt, and 2 tablespoon sugar to a large bowl, whisking to combine. In a medium bowl, whisk together buttermilk, eggs and vanilla. Add wet ingredients to dry ingredients, stirring just until combined (there should still be lumps). Quickly whisk in the melted butter. Let the batter rest until the rhubarb is done (at least 30 minutes).

Preheat a waffle iron according to the manufacturer’s instructions. Fold poached rhubarb (and any syrup left in the bowl) into the waffle batter. Brush the top and bottom plates lightly with melted butter to keep the waffles from sticking. Scoop 1/2 cup of batter in each well*, and using a spatula, spread the batter out to the corners. Close the waffle iron, and cook until golden brown.

While the waffles are cooking, prepare the whipped cream. Add the cream, sugar, lemon zest and lemon juice to the bowl of a stand mixer fitted with the whisk attachment. Whisk on high until soft peaks form.

To serve, plate up 2 waffles, then top with rhubarb syrup, lemon whipped cream and a bit of freshly grated lemon zest.