Preheat the oven to 425°F (220°C).
Brush the sweet potatoes with olive oil and season lightly with salt.
Arrange them cut-side down on a baking sheet.
Roast for 20 minutes, then check for caramelization. Continue roasting for another 10–15 minutes until fork tender.
Meanwhile, heat olive oil in a large skillet over medium-high heat.
Cook the onion until softened.
Add the ground chicken and taco seasoning, breaking up the meat as it cooks.
Stir in the salsa and salt, then simmer for 2 minutes.
Whisk together the yogurt, mayonnaise, chipotle powder, garlic, salt, and water until smooth.
Assemble the Roasted Sweet Potato Stacks by placing each roasted sweet potato on a serving plate, spreading on chipotle sauce, topping with the chicken mixture, and finishing with avocado, cilantro, pickled onions, and crunchy toppings.