Place the salmon in a baking dish, sprinkle with the fresh garlic, season liberally with salt and pepper, squeeze the juice of half of one lemon over the top, and drizzle evenly with 2 teaspoons of olive oil. Cover the baking dish and place in the refrigerator to marinate for 15 minutes.
For the dill sauce, in a small bowl, whisk the yogurt, juice of half of a lemon (1 tablespoon), the dill, garlic powder, and a pinch of salt and pepper. Set aside to let the flavors blend. If you’re waiting longer than 15 minutes before using, cover and refrigerate.
For the cucumber feta salad, in a large bowl, combine the cucumber, onion, and feta. In a small bowl, whisk the juice of the remaining lemon (about 2 tablespoons), the remaining 2 teaspoons olive oil, and a pinch of salt and pepper. Pour the dressing over the cucumber salad and toss to combine.
Remove the salmon from the refrigerator. Spray a large nonstick pan with an oil mister and heat the pan over medium-high heat. When the pan is hot, add the salmon skin-side-down and cook, without moving, until the sides are cooked halfway up the filets, about 5 minutes. Flip and cook until the sides are fully cooked and the fish feels firm to the touch, about 4 minutes.