Cut sweet potatoes into 1/2 inch cubes and spread in a single layer on a baking sheet. Drizzle with avocado oil and pinch with salt and pepper.
Roast sweet potatoes for 30-40 minutes, or until tender, stirring halfway through.
In a large bowl, combine the chopped onion, celery, and chili powder. Add the yogurt and chipotle aioli, and mix again until well combined.
Once the sweet potatoes are done cooking, let cool for 10-15 minutes, then toss into the mixture. Fold in cilantro and squeeze lime, then refrigerate for 2 hours before serving.
