Preheat oven to 425°F and line a baking sheet with parchment paper.
In a medium bowl, toss the diced sweet potato with olive oil, salt, and pepper. Spread evenly on one side of the baking sheet.
Pat the chickpeas dry with a clean kitchen towel. In a separate bowl, toss with salt, pepper, garlic powder, onion powder, cumin, and nutritional yeast. Spread on the other side of the baking sheet.
Roast for 20–25 minutes, stirring halfway through, until the sweet potatoes are tender and lightly caramelized and the chickpeas are crisp.
While the vegetables roast, whisk together the olive oil and lemon juice in a large serving bowl.
Add the spring mix, kimchi, pumpkin seeds, and fennel seeds to the bowl.
Once the sweet potatoes and chickpeas have cooled slightly, add them to the salad and toss gently until evenly combined.
Serve immediately while the chickpeas are still crisp.