In a small saucepan, combine the ingredients for Tangzhong starter. Whisk until no lumps remain.
Place the pan over low heat and cook, whisking constantly, until thick and the whisk starts to leave lines on the bottom of the pan, about 3~5 minutes.
Transfer the starter to a small bowl and let cool to room temperature.
Melt 2tbsp butter in a saute pan, add the chopped jalapenos and pinch of salt; cook till slightly tender, about 3~4 minutes. Take off the heat and let cool to room temperature.
Combine flour(s), sugar, salt, yeast, dry milk, melted 4tbsp butter, milk, egg replacer mixture, cooled jalapenos and the tangzhong starter in a large mixing bowl or the bowl of the stand mixer.
Mix and knead till a smooth, elastic dough forms. Shape the dough into a ball and place it in a lightly greased bowl. Cover and set aside for 60~90 minutes, until puffy but not necessarily doubled in bulk.
Gently deflate the dough and form into a loaf. Place it in a lightly greased 8.5"x4.5" loaf pan. Cover with a greased plastic wrap and set aside for 40~50 minutes.
Preheat the oven to 350F. Brush the loaf with milk (or egg wash) and bake for 28~32 minutes or until the top is golden brown and the digital thermometer inserted into the center reads 190F.
Remove from the oven and transfer to a cooling rack to cool completely before slicing.