In a large mixing bowl, combine all-purpose flour, white granulated sugar, salt, and instant yeast. Incorporate the cold vegan butter, then gradually add cold soy milk until a shaggy dough forms.

Wrap the shaggy dough tightly in plastic wrap and refrigerate for about 1 hour.

Roll the chilled dough into a long rectangle (1/4 inch thick), fold into thirds, then roll and fold into quarters. Repeat this folding technique three more times.

Wrap the folded dough in plastic wrap and refrigerate for another hour.

Divide the chilled dough into two portions, roll one into a rectangle (1/4 inch thick), then slice into triangles. Roll each triangle tightly from the wide edge.

Place the shaped croissants on baking sheets, cover loosely with a kitchen towel, and let proof for about 1.5 hours.

Refrigerate the proofed croissants for 30 minutes. Brush with cold soy milk before baking in a preheated oven at 375°F (190°C) for 18-20 minutes.

Remove from oven and transfer to a wire rack to cool for a few minutes before serving.