Before starting, preheat the broiler to high. Wash and dry all produce. Heat a large non-stick pan over medium heat. While the pan heats, zest lemon.Add turkey, lemon zest, stock powder and breadcrumbs to a medium bowl. Season with pepper, then combine.

Form mixture into two 4-inch-wide patties (4 patties for 4 ppl). (NOTE: Your mixture may look wet; this is normal!) When the pan is hot, add 1/2 tbsp (1 tbsp) oil, then patties. Pan-fry until patties are golden-brown and cooked through, 5-6 min per side.**

Meanwhile, juice half the lemon (whole lemon for 4 ppl). Halve 1 cucumber (2 cucumbers for 4 ppl) crosswise, then thinly slice lengthwise. Cut remaining cucumber into 1/4-inch rounds. Cut tomato into 1/2-inch pieces.

Add 1/2 tbsp (1 tbsp) lemon juice, 1/8 tsp (1/4 tsp) sugar and 1 tbsp (2 tbsp) oil to a large bowl. Season with salt and pepper, to taste, then whisk to combine. Set aside. Combine half the feta and half the tzatziki (use all for 4 ppl) in a small bowl. Season with pepper, to taste, then stir to combine.

When patties are almost done, arrange buns directly on the top rack of the oven, cut-sides up. Broil buns in the top of the oven until golden-brown, 1-2 min. (TIP: Keep an eye on buns so they don't burn!)

Add cucumber rounds, tomato and spinach to the bowl with vinaigrette, then toss to combine. Stack patties on bottom buns, spread tzatziki-feta over patties, then arrange cucumber slices over top. Season cucumbers with a pinch of salt and pepper, then close with top buns. Divide burgers and salad between plates. Sprinkle remaining feta over salad.