Greek Burger with Arugula, Tomatoes, and Feta

Heat oven to 350°F. Cut 1/4 off each pita (a half-moon shape from 10 o'clock to 2 o'clock). Chop half-moons, transfer to a bowl and sprinkle with milk. Let soak 5 minutes. Drain and squeeze out excess milk. Purée soaked bread, onion, garlic, herbs and lemon juice in a blender or food processor. Transfer purée to a bowl. Add lamb, season with salt and pepper and combine. Form into 4 patties. Wrap pitas in foil and heat until warm, about 8 minutes. (Or place pitas between sheets of paper towel and microwave until warm, about 30 seconds.) Heat oil in a nonstick skillet over medium-high heat until hot. Cook burgers to medium, 2 to 3 minutes on each side. Whisk yogurt, mint, garlic, mustard and honey in a bowl. Stir in cucumber and season with salt and pepper. Open each pita, stuff with arugula and drizzle with some of the dressing. Add burger, tomato and red onion to pita. Sprinkle with feta. Serve leftover dressing on the side.