Preheat your oven to 400°F (200°C). On a large baking sheet, toss the halved Brussels sprouts with 1 tablespoon of olive oil, onion powder, garlic powder, sea salt, and ground black pepper. Spread them out in a single layer and roast for 25-30 minutes, or until golden brown and crispy on the edges.
In a medium saucepan, combine the rinsed quinoa and vegetable stock. Bring to a boil, then reduce heat to low and cover. Simmer about 15 minutes until quinoa is fluffy and liquid absorbed. Remove from heat and let sit covered for 5 minutes, then fluff with a fork.
While the Brussels sprouts and quinoa cook, combine soaked cashews, garlic, nutritional yeast, capers, lemon juice, olive oil, Dijon mustard, vegan Worcestershire sauce, hot sauce, and water in a blender or food processor. Blend until smooth and creamy. Season with sea salt and ground black pepper to taste.
In a large mixing bowl, combine cooked quinoa, roasted Brussels sprouts, cooked lentils, pickled red onions, sun-dried tomatoes, and toasted sunflower seeds. Drizzle with spicy Caesar dressing and gently toss to combine.
Taste and adjust seasoning if needed. Garnish with chopped parsley or chives if desired. Serve warm or chilled and enjoy!