Grandma Libia's croquetas

Directions

1. Melt the butter and heat along with the oil on a large frying pan till hot.
2. Add the flour and stir for it to toast, eliminate the raw flour taste and absorb the fat. Mash the lumps with the back of a wooden spoon, till you have a crumbly mixture and all the fat is absorbed, around 5 minutes.
3. Add half of the milk and stir continuously for a while, while breaking the lumps and thickening the mixture.
4. Add a table spoonful of salt.
5. When the mixture is thickened a little bit, add the rest of the milk. If too many lumps are left, you can just use a hand mixer to break them and make the mixture more even.
6. Add the tuna garnish, previously drained and flaked, and keep on stirring to thicken.
7. When the mixture starts to separate from the pan walls and it's thick enough to shape it, turn the heat off (yeah, I know this is tricky if you've never seen the real consistency. But you have to be careful, if the dough is too runny, the croquetas will burst the coating on frying... they should be solid enough).
8. Try the salt and add more if necessary (it will be).
9. Add the nutmeg and stir.
10. Pour the whole thing on a shallow dish to cool. Cover with a plastic wrap that touches the surface, so that no crust is formed on cooling.
11. When the dough is at ambient, take small portions with a table spoon and use 2 spoons to shape them into oval patties.
12. Beat 2 or 3 eggs in a container and coat the patties in egg.
13. Roll them in breadcrumbs.
14. When all the croquetas are prepared, heat the oil in a deep pan. Deep-fry them in very hot oil (I fry them in a deep-fryer, at maximum temperature of 190ºC)