1. In a frying-pan, heat 1 tbsp olive oil and fry the garlic until fragrant and add the onion, cook until lightly browned.
2. Add the butter and melt completely, then add the flour. Stir and mix well.
3. Add milk little by little and continue simmering until thick, stirring occasionally with a spatula.
4. Add kosher salt, soy sauce, sugar and pepper. Mix.
5. Add, scallion, shrimps, crab sticks and mix well. (or shrimps, brown mushroom)
6. Remove from the heat and transfer the mixture on a plate or a baking pan. Leave it to cool. Then cover with plastic wrap and keep it in the fridge (or freezer if you are in hurry.) for about 1h or more until it's firm.
(The mixture is very soft, so better make it firm well so that easy to handle for the next steps.)
7. Lightly wet your hands with water and make small portions. The shape can be rough at this stage, it does not matter too much.
8. Dip each croquette (in this order) in flour, egg then panko. Make sure to coat with panko evenly all around, making the croquette into a nice round shape.
9. In a large cooking pot, heat the oil on medium-high heat to about 170C degree or until small bubbles appear around your chopstick. Deep fry 2 or 3 croquettes until all sides are nicely brown.
10. Transfer to a plate lined with paper towel to drain off the excess oil. Repeat with the remaining croquettes.