Set your oven to 400°F (200°C) and allow it to preheat fully.
Spread the sweet potato cubes across a parchment-lined baking sheet. Drizzle with a tablespoon of olive oil and toss to coat. In a small dish, combine paprika, garlic powder, ½ teaspoon salt, and a few grinds of black pepper. Sprinkle this seasoning blend evenly over the sweet potatoes and mix until every piece is well coated.
Roast the seasoned sweet potatoes for 13 to 15 minutes, give them a stir, then return to the oven for another 13 to 15 minutes, or until golden and fork-tender.
Meanwhile, in a spacious mixing bowl, whisk together 2 tablespoons olive oil, apple cider vinegar, honey (or agave), 1 teaspoon kosher salt, and ground cumin until the dressing is well blended. Stir in the red onion so it can slightly soften while the potatoes roast.
As soon as the sweet potatoes come out of the oven, while still hot, add them directly into the bowl with the dressing and onions. Toss thoroughly to coat the warm potatoes, then let them sit and cool for at least 5 minutes.
Once the potatoes have cooled slightly, add the arugula and kale to the bowl. Drizzle with the remaining teaspoon of olive oil and sprinkle with ⅛ teaspoon of salt. Gently toss until the greens are evenly dressed and combined with the sweet potatoes.
Portion the salad into four bowls, finishing each serving with a quarter of the diced avocado. Adjust seasoning with extra salt and pepper as desired before serving.