I recently purchased this vegetable at a farmers' market without getting its name. It was marketed as organic/fresh/local in the Northeastern United States in late September.
The leaves are thin and non-waxy, but a little moist (when I try to slide my fingers across the leaves they stick a little).
When I tasted a small portion of a leaf raw, I immediately felt moderate burning in the mouth which I (mistakenly) believed to be oxalic acid at first. In reality, it was a mustardy spicy/sharp taste (which I didn't expect from greens). Because I don't know the name of this plant, I'm not sure if this is the case. In light of that concern, does it require any special preparation to be safe for healthy individuals?