Make the slurry: In a bowl, whisk potato starch and salt. Pour in the hot water in a slow stream while stirring constantly. The mixture will turn translucent and thicken quickly. Aim for a smooth, pourable batter—like pancake batter. If it’s too thick to pour, add 1–2 tablespoons of hot water.

Prepare the steamer: Bring water to a simmer in your steamer or lidded pan. Lightly oil your heatproof tray or shallow dish with a pastry brush.

Steam the first sheet: Pour a thin layer of batter into the tray—just enough to cover the surface (around 2–3 mm thick). Place the tray into the steamer, cover, and steam for 3–4 minutes. The sheet is ready when it turns fully translucent and slightly shiny.

Cool and release: Carefully remove the tray. Brush the surface with a little oil to keep it from sticking. Let it cool for 1–2 minutes, then peel the sheet off the tray. Set it on a lightly oiled cutting board.

Repeat: Re-grease the tray, give the batter a stir, and steam the next sheet. Continue until all batter is used. You should get 5–6 sheets.

Slice into noodles: Stack 2–3 cooled sheets and cut into 1/2-inch-wide ribbons (or thinner if you like). Gently fluff the noodles with oiled fingers to separate.

Make the sauce: In a bowl, whisk tamari, rice vinegar, sesame oil, garlic, ginger, chili oil, and sugar. Taste and adjust—add vinegar for brightness, chili for heat, or a pinch more sugar if it’s too salty.

Combine: Toss noodles with sauce in a large bowl. Add scallions, sesame seeds, and any extras like cucumber, spinach, tofu, or chicken. Serve warm or at room temperature.