For the crema: 2 chipotle chilies in adobo sauce, 1/2 cup Mexican crema or sour cream
Preheat oven to 400°F. Season the cauliflower florets with olive oil, ground cumin, garlic powder, salt and pepper, lime zest and its juice. Spread out on a parchment-lined baking sheet, and roast for about 30 minutes. Toss occasionally, until tender and golden brown.
Meanwhile, add chipotle chilies and Mexican crema in a food processor. Blend until smooth.
To assemble, heat tortillas by charring them slightly over a stove burner, add a layer of sliced avocado, the roasted cauliflower, chipotle crema, sliced jalapeño, and cilantro.