Preheat the oven to 350F. Line a baking sheet with parchment paper. Add the seeds, paprika, garlic, oil, and salt and toss to coat evenly. Spread into an even layer, then bake for 8-10 minutes, stirring halfway through. Let cool.
In a medium pot over medium-high heat, add 1 tablespoon oil, onion, and ½ teaspoon salt. Cook until the onion has softened, about 3-5 minutes, stirring occasionally. Add cumin and coriander and cook for 30 seconds, stirring constantly.
Add potatoes, water, and remaining 1 teaspoon salt. Cover, bring to a boil over high heat, then reduce the heat to low/medium-low and simmer (covered) for 15 minutes or until potatoes are totally soft and cooked through. Stir in the spinach.
Transfer to a high-speed blender along with the tahini or almond butter and lemon. Blend until totally smooth, making sure to carefully let the steam escape as you blend. Taste and add more lemon, if needed.
Serve topped with plenty of spiced seeds, feta, parsley, black pepper, and a drizzle of good olive oil. Serve with toast (if using).