Preheat your oven to 425°F / 220°C. On a large baking sheet, toss the diced sweet potatoes with 1 tsp (5 ml) olive oil, salt, and pepper.
Spread them in a single layer and roast for 15-20 minutes, stirring halfway through, until tender and lightly caramelized.
While the potatoes roast, combine the rinsed quinoa and 2 cups (480 ml) of water in a small saucepan.
Bring to a boil, then reduce the heat to a simmer, cover, and cook for 15 minutes or until the water is absorbed and the quinoa is tender. Fluff with a fork and season with salt.
To prepare the chimichurri, gently warm the 1/4 cup (960 ml) of olive oil in a small saucepan over medium heat.
In a food processor, combine the parsley, lemon juice, minced garlic, paprika, and red pepper flakes. Pulse until coarsely chopped. With the processor running, slowly stream in the warm oil and pulse until just blended.
Assemble your bowls by dividing the cooked quinoa and roasted sweet potatoes among four servings.
Top each with about 3 tablespoons (45 ml / 1.5 fl oz) of chimichurri, and garnish with fresh avocado slices, if using.
Drizzle with extra sauce if desired.