Heat oven to 450 degrees. On a baking sheet, combine the sweet potatoes, oregano, salt, and half the oil. Toss well and roast for 40 minutes, or until tender and golden, flipping once halfway through. Remove from oven.
Meanwhile, in a skillet, lightly toast the pumpkin seeds over medium heat, stirring occasionally, about 5 minutes. Remove from heat. Add the garlic, lemon juice, and the remaining oil and stir together. Add the sweet potato wedges and toss well.