Before You Start: I highly encourage you to weigh your flour and butter using a kitchen scale. For weights, click the Metric button above. If you don't have a scale, here's how to measure flour with a measuring cup: Fluff the flour with a spoon, sprinkle it into the measuring cup, and level it off. Otherwise, you may scoop more than you need.
Gather all the ingredients.
To Make a Brown Roux
In a small saucepan, melt 3.5 oz unsalted butter over medium-low heat (you can also add cubed butter and start with medium heat, so it melts faster).
When the butter is completely melted, add 3.5 oz all-purpose flour (plain flour). With a blunt-end wooden spatula, stir to combine the butter and flour.
Soon, the butter and flour will fuse and swell. For the next 20–25 minutes, control the stove's heat to around medium-low heat, and stir constantly because the roux burns easily. Nami's Tip: If the roux starts separating, switch to a whisk and mix vigorously.
The roux will turn golden brown quickly toward the end. See the "brown roux" color in the next step. Nami's Tip: Cooking the flour in butter until golden removes its raw, starchy taste and adds a warm, toasty flavor that makes your curry richer and smoother.
To Make the Curry Roux
Add 4 Tbsp Japanese 1 Tbsp and ½ tsp to the roux. Tip: If you can‘t find you can add more or individual spices in its place.