Quinoa: Toast the quinoa in a pan in some olive oil until golden, and then add 1 ⅓ cup water and a pinch salt. Stir to mix and bring to boil. Cover the pan and lower heat to lowest setting, cook for 25 mins. Remove from the heat and leave covered for 5 mins, then fluff. I let it cool to room temp for this dish.
Sweet potato: Preheat oven to 375. Peel and dice the potato into bite-sized cubes. Place on a sheet tray and drizzle with olive oil. Sprinkle with a light dusting of cumin, season with salt and pepper, then toss to evenly coat. Roast for 25 mins. Allow to cool to room temp.
Dressing: In a small bowl, add the garlic, lime juice, ½ tsp cumin (or to taste), salt and pepper to taste, and then add olive oil in a slow stream as you mix to combine. Taste and adjust seasoning according to taste.
Assemble salad: In a large bowl, combine all ingredients and toss to mix thoroughly. Add the dressing and toss again, tasting for seasoning and adjusting as needed.