In a small saucepan, combine the vinegar, water, salt, sugar and jalapeño. Heat until a gentle boil and allow to cook for about 2 to 3 minutes. Place the thinly sliced red onion in a bowl or glass measuring cup. Pour vinegar mixture over the red onions and stir until the onions are completely submerged. Set aside. (Should pickle in about 1 hour and can keep in the fridge for up to 3 months in an airtight jar.) 

To a blender or food processor, add the sour cream, avocado, jalapeño, lime juice and 1/4 teaspoon of salt. Pulse until very smooth, scraping down the sides as needed. Give it a taste and adjust the salt to taste (I ended up adding a few more pinches of salt). 

In a small bowl, whisk together the olive oil, ancho chile powder, salt, paprika, cumin, oregano and cayenne. 

To another small bowl, add the pepitas and add 1 tablespoon of the spiced olive oil mixture to them. Toss until combined. Set aside. 

Preheat the oven to 425 degrees F. Add the cauliflower florets to a parchment-lined baking sheet. Pour the oil mixture over the cauliflower and toss until evenly coated in the oil mixture. Transfer to the oven and roast for about 15 to 17 minutes, until the cauliflower is tender. 

Meanwhile, in a small skillet, set over medium heat, add the pepitas. Toast the pepitas until lightly browned, about 1 to 2 minutes. Transfer to a small bowl and allow to cool. Once cooled, roughly chop them up and set them aside until serving. 

Halve and lightly toast Ozery Bakery buns and then add a liberal dollop of avocado creama to each half bun. Smear it to the edges and then top with a few pieces of pickled red onion. Add a few spoonfuls of cauliflower florets and garnish with pepitas, radishes and cilantro.