Preheat your oven to the lowest setting, around 86°F (30°C). Place a bowl of boiling water inside to create a steamy environment for the dough.

In a stand mixer, combine water, bread flour, bread improver, instant dry yeast, sugar, and vitamin C powder. Mix on low until incorporated, then knead on medium for about 8 minutes until smooth and elastic.

Transfer the dough to a lightly floured surface. Divide into six equal pieces, each weighing about 3.5 ounces, and shape each into a log approximately 8-10 inches long.

Place the shaped logs on parchment paper on a baking sheet. Return to the warm oven and let proof for 1.5 to 2 hours until quadrupled in size.

After proofing, increase oven temperature to 400°F (200°C) and prepare a steaming method with an iron skillet filled with water.

Carefully transfer the proofed baguettes to a baking sheet and score the tops at a 45-degree angle with a razor blade.

Pour hot water into the preheated skillet and place the baking tray in the oven. Bake for 7-8 minutes with steam, then remove the skillet and bake for an additional 4-5 minutes until golden brown.

Cool the Bánh Mì on a wire rack for a few minutes, then brush the crusts with melted vegan butter for a shiny finish.