Preheat oven to 400°F (200°C). Line a baking sheet with parchment paper.
Toss diced sweet potatoes with 1 ½ tablespoons olive oil, smoked paprika, thyme, salt, and pepper. Spread on the sheet pan in a single layer. Roast for 15 minutes.
While potatoes roast, season salmon fillets with 1 tablespoon olive oil, garlic, salt, and pepper.
Remove pan from the oven and add salmon fillets and green beans around the sweet potatoes. Return to oven for 10–12 minutes until salmon flakes with a fork.
Toss kale with ½ tablespoon olive oil. Scatter it around the pan in the last 5–6 minutes of roasting so it crisps but doesn’t burn.
Once salmon is cooked and kale is crisp, squeeze lemon juice over everything. Add optional toppings if desired. Serve warm.