Spring Vegetable and Prosciutto Tart / Jill Silverman Hough

Ingredients

• 1 leek, white and light green parts only, cut into 1/4-inch slices
• 3 ounces snap peas, cut into 1/2-inch lengths (you should have about 3/4 cup) (see note)
• 3 small white or red potatoes (about 4 ounces), cut into 1/8-inch slices
• 1 sheet (half of a 17.3-ounce package) puff pastry, thawed
• 1 1/4 cups shredded Gruyère cheese (about 4 ounces), divided
• 2 thin slices prosciutto (about 1 ounce), cut into 1/4-inch strips
• 1 1/2 teaspoons chopped fresh flat-leaf parsley
• 1 1/2 teaspoons chopped fresh mint, tarragon, or a combination
• 1 lemon wedge