Preheat the oven to 425F and line a baking sheet with parchment paper or foil.

Make the pickled onions beforehand: Put distilled white vinegar and water in small pot with sugar and salt. Bring to rapid boil, stirring to ensure the sugar and salt are dissolved. In the meantime, slice the onion into thin half-circles and put the slices into a glass container like a mason jar or Pyrex. Once vinegar and water mixture (brine) has come to a boil, remove from heat for a few seconds and then pour over top of the onions. Let sit for 30 minutes, then put into fridge for at least 1 hours.

Combine cauliflower, sweet potatoes, olive oil, chili powder, cumin, smoked paprika, garlic powder, oregano, and kosher salt in a large mixing bowl and toss well to combine.

Spread cauliflower and sweet potatoes on baking sheet, and put in oven 15-20 minutes, until fork tender.

Make chipotle lime crema: In a food processor, add the Greek yogurt, chipotles, lime juice, honey, salt, and garlic. Pulse until the peppers and garlic are completely pureed and the sauce is smooth. Add ½ - 1 tablespoon of water to thin the sauce out more, if desired.

Make avocado mash: Spoon avocado into bowl with lime juice and salt to taste. Roughly mash, and then spread on face of tortilla.

Assemble: put cauliflower and sweet potatoes on top of avocado mash. Place pickled onions on top and drizzle chipotle lime crema on top. Garnish with cilantro and enjoy immediately.