Slice 1 lemon half into 4 thin rounds and set aside. Grate the zest of the other lemon half and set aside; squeeze some of the juice into a bowl and mix in the yogurt and 1/4 teaspoon paprika. Preheat the broiler. Heat 1 teaspoon olive oil in a medium saucepan over medium heat. Add the garlic, oregano and red pepper flakes and cook until the garlic is golden, about 2 minutes. Add the lima beans, 1 1/2 cups water and the lemon zest; partially cover the pan, bring to a simmer and cook until the beans are tender, about 20 minutes. Season with salt and pepper. Remove from the heat and stir in the parsley, 1 tablespoon of the yogurt mixture and the remaining 1 teaspoon olive oil. Meanwhile, mix the remaining 1/2 teaspoon paprika, 1/2 teaspoon salt, and pepper to taste in a small bowl. Sprinkle all over the salmon; arrange on a foil-lined baking sheet and top each fillet with a lemon slice. Broil until just cooked through, 6 to 8 minutes. Serve with the lima beans and top with the yogurt mixture.