Potato Quiche with Spinach - Crynfiction

Ingredients

• 1 1/2 pounds baby yellow potatoes, thinly sliced
• 1 cup thinly sliced yellow onion
• 1 1/8 teaspoons kosher salt, divided
• Cooking spray
• 7 tablespoons olive oil, divided
• 3large eggs
• 2large egg whites
• 1 1/2 ounces feta cheese, crumbled (about 1/3 cup), divided
• 1 tablespoon red wine vinegar
• 1 tablespoon fresh lemon juice
• 1 teaspoon honey
• 4 cups baby spinach leaves
• 2 cups halved grape tomatoes
• 1 cup sliced English cucumber
• 1 cup sliced red bell pepper