The oven method: 

1. Cook the quinoa: Combine the quinoa, salt, and water in a small saucepan and cook according to package instructions—fluff with a fork.
2. Roast the vegetables: Preheat the oven to 425°F (220°C). Arrange the onion, bell pepper, and pumpkin on a baking tray. Drizzle with olive oil and season with salt, black pepper, garlic powder, and oregano. Toss to coat and spread into an even layer. Roast for 30 minutes until fork-tender. Flip the vegetables and broil on high for 5 minutes for extra caramelization.
3. Make the tahini dressing: Follow the recipe here. It takes 5 minutes.
4. Assemble the quinoa bowl: Divide the quinoa among four bowls. Top with the roasted vegetables and sprinkle with fresh parsley. Drizzle with Tahini Dressing and serve immediately.

The sous vide method: 

1. Set up the sous vide: Preheat water to 185°F (85°C) using a sous vide machine. 
2. Prepare the vegetables: Place the onions and bell peppers in a sous vide bag and the pumpkin in another. Respectively drizzle the bags with olive oil and season with salt, black pepper, garlic powder, and oregano. Shake to coat. Arrange vegetables in one single layer in each bag and vacuum seal the bags. 
3. Sous vide the vegetables: Place the two sous vide bags in the heated water bath. Weigh them down to ensure the vegetables are fully submerged in the water. Set the timer for 15 minutes. Once the timer goes off, remove the bag with the onions and bell peppers and leave the pumpkin in the sous vide bath to cook for another 30-45 minutes until tender. 
4. Cook the quinoa: Combine the quinoa, salt, and water in a small saucepan and cook according to package instructions—fluff with a fork.
5. Assemble the quinoa bowl: Divide the quinoa among four bowls. Top with the sous vide vegetables and sprinkle with fresh parsley. Drizzle with Tahini Dressing and serve immediately.