Preheat the oven to 375 degrees F. Cut the pumpkin into about 3-inch chunks and arrange on a rimmed baking sheet skin-side down. Drizzle the pumpkin pieces with olive oil and give them a sprinkle of salt and pepper. Roast the pumpkin until soft, about 1 hour. Once it is cool enough to handle, peel off and discard the skin, and place the roasted pumpkin flesh in a bowl.
Meanwhile, place a large dry skillet over medium heat and add the quinoa. Toast for 5 to 10 minutes or until the quinoa releases a beautiful toasty aroma. Add 3 cups of water and 1 tablespoon salt; cover and bring to a boil. Reduce the heat to low and simmer the quinoa until all the water has been absorbed, about 25 minutes. Remove from the heat and set aside, covered; the steam will finish cooking the quinoa.
Once the quinoa has cooled a bit, add it to the bowl with the roasted pumpkin along with the dates, torn sage leaves and 1/4 cup olive oil. Toss gently to combine. Season with more salt and pepper. Serve at room temperature.