In a small bowl, soak the sun-dried tomatoes in very hot tap water until softened, about 10 minutes. Drain and pat dry.
While the tomatoes soak, prepare the onion.

• Peel and thinly slice half the onion. Finely chop enough of the remaining onion to measure ¼ cup [½ cup]; set aside for the lentil salad.

In a medium frying pan over medium heat, warm 1 teaspoon [2 tsp] oil until hot but not smoking. Add the sliced onion, season with salt and pepper, and cook, stirring occasionally, until soft and caramelized, 8 to 10 minutes. Remove from the heat and season to taste with salt and pepper.
While the onion cooks, prepare the burgers.

• Cut a small corner from the ground turkey package and drain off any excess liquid. Transfer to a plate; pat dry with a paper towel.
• Zest the lemon; juice half and cut half into wedges. [Zest both lemons; juice 1 lemon and cut the remaining lemon into wedges.] Set aside the juice for the lentil salad and the wedges for garnish.
• Remove any thick stems from the parsley, then coarsely chop.

In a medium bowl, combine the turkey, lemon zest, and parsley. Season generously with salt and pepper and mix gently until just combined. Using wet hands, form the mixture into four [eight] ½-inch-thick patties.

In a large frying pan over medium-high heat, warm 1 to 2 tablespoons oil until hot but not smoking. Add the patties and cook, turning once, until browned and cooked through, 4 to 6 minutes per side. Transfer to a plate.
While the burgers cook, prepare the lentil salad.

• Finely chop the dates.
• Rinse the lentils.
• Coarsely chop the sun-dried tomatoes.
• Trim the root end from the lettuce; remove 4 [8] of the largest outer leaves for the burgers and save the remaining lettuce for another use.

In a medium bowl, stir together the dates, 1 tablespoon [2 TBL] lemon juice, and 2 teaspoons [4 tsp] oil; season with salt and pepper. Add the lentils, sun-dried tomatoes, finely chopped onion, and oregano and toss to combine; season to taste with salt and pepper. 

Transfer 2 lettuce leaves to each individual plate. Top each leaf with a burger, 1½ to 2 teaspoons green goddess dressing, and caramelized onion. Serve the lentil salad and lemon wedges on the side.