Preheat your oven to 400°F. Line a large baking sheet with parchment paper.
Make the peanut sauce. In a medium bowl, whisk together the peanut butter, ginger, lime juice, tamari, salt, pepper, and water. Once you have a totally smooth and slightly fluid sauce, you’re good! Check for seasoning, adjust if necessary, and set aside.
In a large bowl, toss the sweet potatoes with 1 tablespoon of the olive oil, 1 teaspoon of garlic powder, 1 teaspoon of paprika, 1 teaspoon of ground cumin, salt and pepper. Once you have the sweet potatoes evenly coated, spread them out on the baking sheet and transfer to the oven. Set a timer for 30 minutes.
While the sweet potatoes are roasting, give your chickpeas a quick dry with a kitchen towel. Then, add the chickpeas into the large bowl along with the grape tomatoes, chopped broccoli rabe, the remaining tablespoon of olive oil, ½ teaspoon garlic powder, ½ teaspoon paprika, ½ teaspoon ground cumin, salt, and pepper. Give everything a thorough toss to make sure that all is coated.
Once the timer goes off, retrieve the sweet potatoes from the oven Using a spatula, flip over and push the sweet potato pieces to the outer edges of the sheet pan. Then, transfer the chickpeas, tomatoes, and broccoli rabe to the cleared area of the sheet pan. Spread everything out evenly and place the sheet pan back in the oven. Roast this mixture for another 20 minutes, or until the sweet potatoes are tender and golden brown and the broccoli rabe pieces are wilted and soft.
Remove the sheet pan from the oven and drizzle the vegetables with the peanut sauce (there will be extra). Top everything with the diced red onion, pumpkin seeds, and chopped herbs. Enjoy immediately!