Place sweet potatoes in a bowl and drizzle a tiny bit of olive oil. Give a good pinch of salt (about 2 tsp), some pepper, and any other seasoning you want. I usually do a tsp of garlic powder. Toss sweet potatoes to coat evenly.
Spread potatoes on baking sheet and roast for 20 minutes.
While those are cooking, mash an avocado in a bowl until smooth. Stir in yogurt, juice from a lime, salt and pepper to taste, and fresh herbs.