Preheat the oven to 400 degrees F. Line a large baking sheet with parchment paper.
In a small bowl, add the spices: paprika, cumin, garlic powder, turmeric, thyme, salt and a few grinds of black pepper. Mix until well combined.
Place potatoes, chickpeas and onions on the prepared baking sheet. Drizzle with 2 tablespoons of olive oil, then sprinkle with 1 tablespoon of the spice mixture. Toss until well coated then spread into an even layer. Bake for 20 minutes.
Place the yogurt, leafy herbs, garlic, lemon juice and salt in a blender or food processor. Blend on high until well combined, about 30 seconds. Taste and adjust seasonings as necessary. Set aside until ready to serve.
Drizzle the salmon with remaining 1 tablespoon of olive oil and rub into the flesh of the salmon. Evenly sprinkle the remaining spice mixture on the salmon.
Once potatoes and chickpeas are done cooking, remove from the oven and gently flip and push to the edges, making space for the salmon. Add salmon fillets wherever you can fit them and bake for 10 to 15 more minutes until salmon is perfectly cooked to your liking.
Remove from the oven and immediately drizzle with a few tablespoons of the herby yogurt sauce. Add on feta crumbles, lemon zest and extra dill and parsley. Serve over a bed of arugula and more sauce if desired.