Place flaked salmon in a large bowl and check for any remaining bones; remove. Add the finely chopped onion, minced parsley, Dijon mustard, lemon juice, mayonnaise, 1/4 cup panko (for binding), egg, 1 tsp salt and 1/2 tsp black pepper. Gently mix until combined but not overworked — you want some texture. If mixture seems too wet, add up to 1–2 tbsp additional panko.

Form cakes

Divide mixture into three equal portions. With lightly wet hands, shape each portion into a compact patty about 3/4-inch thick and 3 inches across. Chill on a plate in the refrigerator for 15 minutes to help them hold their shape (optional but recommended).

Crust and cook

Place 3/4 cup panko in a shallow dish. Press each chilled patty gently into the panko to coat both sides, pressing firmly so the crumbs adhere. Heat a large skillet over medium heat and add 3 tbsp olive oil. When oil shimmers, add the cakes (work in batches if necessary) and cook 3–4 minutes per side until golden brown and an instant-read thermometer reads 135–140°F in the center (or until heated through and crust is crisp). Transfer cooked cakes to a paper-towel-lined plate and keep warm in a low oven (200°F) while finishing the rest.

Finish

If desired, squeeze a little lemon juice over the hot cakes before plating.

Cucumber Yogurt Tzatziki

Grate the seeded cucumber on the large holes of a box grater, then gently squeeze out excess moisture using a clean kitchen towel or paper towels until mostly dry. Combine the grated cucumber with 1/2 cup Greek yogurt, minced garlic, chopped dill, 1 tsp lemon juice, 1 tsp olive oil, 1/4 tsp salt and 1/8 tsp black pepper in a small bowl. Stir until smooth and chill for at least 10 minutes to let flavors meld.

Agave Vinaigrette

In a small jar or bowl, combine 3 tbsp olive oil, 1 tbsp apple cider vinegar, 1 tbsp agave syrup, 1/2 tsp Dijon mustard, 1/4 tsp salt and 1/4 tsp black pepper. Whisk or shake vigorously until emulsified. Taste and adjust seasoning.

Mixed Greens & Assembly

Toss the 3 cups mixed greens, halved cherry tomatoes and sliced cucumber with 1–2 tbsp agave vinaigrette (reserve extra vinaigrette for passing). Arrange a portion of dressed greens on each plate.

Place three panko-crusted salmon cakes atop or beside the greens. Spoon about 2 tbsp cucumber yogurt tzatziki next to the cakes (about 1 tbsp per cake), and garnish with a lemon wedge. Serve immediately while cakes are warm and crust is crisp.