Using butter to stir-fry flour not only multiplies the aroma but also makes the soup thick and delicious.
Many Western dishes have similar steps for enhancing aroma and thickness.
This step requires quick stir-frying over low heat, keeping the temperature in the pan as low as possible, making the sauce both fragrant and thick, and very tasty.
After the aroma emerges, continue to stir-fry for a while until the dough in the pan turns slightly yellow, which in the industry is referred to as "sprout yellow," like the color of a plant just sprouting.
Once it's at this stage, add half a spoon of tomato paste to the pan and continue stir-frying.
Previously, the butter was only slightly sticky, but with flour, it immediately becomes a thick paste. Now, with tomato paste, the butter dough forms a clump.
Tomato paste is very water-absorbent during the stir-frying process.
