Flour

It comes down to protein

• Bread flour, 12%+ — builds a lot of gluten. Bread, noodles like Kalguksu.
• Plain / all-purpose, 10–11% — the general case. Mandu wrappers, most everyday cooking.
• Cake flour, 8–9% — little gluten, so it stays tender. Cakes, pancakes like Gamja Jeon, frying batter.

No cake flour? Replace 10–20% of plain flour with starch.

When you want gluten and when you avoid it

Kneading builds the gluten network; resting relaxes it. Two different jobs.

• Want it — anything that should be chewy. Kalguksu, Mandu wrappers, bread.
• Avoid it — anything that should be tender. Batters for Gamja Jeon or Tempura are mixed as little as possible. Gnocchi is barely worked at all — knead it and you get erasers.

"Knead dough well" is only half true. Details in Dough and gluten.

Measure it by weight

Flour runs 125g per cup spooned and levelled, or up to 150g scooped and packed. A 20% swing changes a bake completely. To convert a cup-based recipe, use the cups-to-grams tool.

Pre-mixed flours are not flour

Korean buchim-garu (pancake mix) and twigim-garu (frying mix) contain salt, starch, baking powder and seasoning. When a recipe says flour it means flour — substituting a mix double-seasons the dish.

Cooked in fat it becomes something else

Flour cooked in butter or oil is a roux: it thickens a sauce while cooking out the raw flour taste. The longer you cook it, from white to brown, the deeper the flavour and the weaker the thickening power.

Storing

• Sealed at room temperature, six months to a year. Wholemeal contains fat and oxidises, so refrigerate or freeze it and use within three months.
• Insects and moisture are the real risks. Move it out of the paper bag into a sealed container.
• Old flour smells musty. If it does, throw it out — that smell carries straight through into whatever you bake.