Preheat your oven to 400°F and line a large sheet pan with parchment paper for easy cleanup.
In a large mixing bowl, combine the cubed sweet potatoes, crumbled tempeh, diced bell peppers, and diced red onion.
Drizzle with olive oil and sprinkle with nutritional yeast, smoked paprika, garlic powder, sea salt, and black pepper, tossing well to coat every piece.
Spread the hash mixture in a single, even layer onto the prepared sheet pan to ensure the vegetables roast rather than steam.
Bake for 25-30 minutes, tossing the ingredients halfway through, until the sweet potatoes are fork-tender and the tempeh crumbles are golden brown.
While the hash roasts, whisk together the Greek yogurt, lemon juice, and chopped chives in a small bowl until smooth.
Remove the pan from the oven and divide the hash into meal prep containers, serving each portion with a generous dollop or drizzle of the herb yogurt sauce.