1. Place quinoa in a mini food processor; process 1 minute or until finely ground. Add chopped walnuts to processor; process until smooth.
2. Place zucchini in a colander, and sprinkle with 1/4 teaspoon salt. Toss well. Let stand 10 minutes, tossing occasionally. Press zucchini between paper towels until barely moist.
3. Combine zucchini, green onions, dill, 1/2 teaspoon pepper, remaining 1/4 teaspoon salt, cheese, and eggs in a large bowl; stir to combine. Sprinkle quinoa mixture over zucchini mixture; stir well to combine.
4. Heat a large nonstick skillet over medium heat. Add 1 tablespoon oil to pan; swirl to coat. Add 4 (1/3-cup) zucchini batter mounds to pan; flatten into 3-inch cakes. Cook 4 minutes on each side or until browned. Remove from pan; keep warm. Repeat procedure with remaining 1 tablespoon oil and batter to yield 8 cakes total.
5. Combine remaining 1/4 teaspoon pepper, yogurt, cucumber, and garlic in a small bowl. Divide greens evenly among 4 plates. Top each serving with 2 cakes and about 1/4 cup cucumber mixture. Serve immediately.