Preheat oven to 350°. Line a 12-cup muffin pan with cupcake liners.
Make cupcakes: In a large bowl, whisk together flour, sugar, cocoa, baking soda, and salt. In a separate bowl, whisk together 1 cup water, the oil, vinegar, and vanilla. Pour wet mixture into dry mixture and whisk until just combined.
Divide batter among cupcake cups. Bake until a toothpick inserted into a cupcake comes out clean, 15 to 20 minutes. Let cupcakes cool completely in pan.
Make frosting: Using an electric mixer, beat shortening, 2 2/3 cups powdered sugar, and the vanilla together to mix. Beat in nondairy milk 1 tbsp. at a time and beat until frosting is smooth and fluffy.
Cut tops off cupcakes and set aside. Smooth about 1 tbsp. frosting onto each cupcake and cover with a few strawberries. Replace top, then add a dollop of frosting and a few tiny slices of strawberry. Put remaining 1 tbsp. powdered sugar in a fine-mesh strainer and dust cupcakes with sugar.
Note: Nutritional analysis is per cupcake.