Cupcakes: Preheat oven to 350. Line tweleve 2 1/2-inch muffin cups with paper bake cups. Coat cups with nonstick cooking spray. Set aside.
In a bowl, gently stir together diced strawberries and orange marmalade; set aside.
In a medium bowl, combine flour, baking powder, baking soda, and salt; set aside.
In a small bowl, whisk together buttermilk, sugar, oil, egg, and vanilla. Add buttermilk mixture to flour mixture. Whisk just until combined. Add finely shredded orange peel and gently stir.
Spoon 1/2 of the batter into prepared muffin cups. Evenly spoon strawberry mixture over batter in muffin cups. Bake 14-16 minutes or until a toothpick inserted near centers comes out clean. Cool in muffin cups on a wire rack.
Frost cooled cupcakes with frosting. Store frosted cupcakes in refrigerator. Garnish with orange peel strips and fresh strawberry slices before serving.
Orange Cream Cheese Frosting: In a medium bowl, beat Neufchatel with an electric mixer on medium speed until smooth. Beat in greek yogurt. Stir in marmalade (frosting will thin slightly). If desired, tint frosting pink with a few drops red food coloring. Cover and chill frosting 4-24 hours before piping on cakes.