Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper.
In a large mixing bowl, combine the cauliflower florets and the rinsed, peeled lupini beans.
Drizzle with olive oil and sprinkle with sea salt, black pepper, garlic powder, and nutritional yeast, tossing until every piece is evenly coated.
Spread the mixture in a single layer on the prepared baking sheet, ensuring enough space for the cauliflower to roast rather than steam.
Roast for 20 to 25 minutes, tossing halfway through, until the cauliflower is tender and develops golden-brown caramelized edges.
While the vegetables roast, prepare the dressing by whisking together the tahini, lemon juice, and water in a small bowl until a smooth, pourable consistency is reached.
Transfer the roasted cauliflower and beans to a serving bowl or plate.
Drizzle the lemon-tahini sauce over the top and garnish with hemp hearts and pumpkin seeds for added crunch and protein.