First, make the whipped feta. Place the feta, yogurt, lemon juice, and lemon zest in a blender. Blend until smooth. Remove from the blender, place into a container with a lid, and put the whipped feta in the fridge.

Melt the butter and whisk in the sriracha. Trim any excess stem off of the cauliflower. Slice the cauliflower into three large pieces. Use a brush to brush the butter and sriracha mixture all over the cauliflower.

Heat a grill to 400 degrees. Place the pieces of cauliflower on the grill, cover the grill, and cook for about 6 minutes and flip. If the cauliflower sticks to the grill at all, brush it with a bit of olive oil. The cauliflower will take about 20 minutes to cook, flip it 3-4 times cooking all sides. You want it to be tender and slightly charred.

Serve the cauliflower immediately, with the whipped feta on the side.