kroketten and bitterballen
© Christianne Muusers

How do you make a kroket or bitterbal? First you prepare a ragout. This ragout, can be varied upon in many ways. Not only can the main ingredient be different (meat, fish, shrimp, vegetables), but of course the herbs and spices, the used liquid (stock, wine, milk, even plain water), and added ingredients (fried onions, bacon or mushrooms) can be changed too. Then the kroket is breaded and deepfried. 
Because I use meat that was used in making stock, here is a link to the page with the basics on stock-making.

Ingredients:
600 gram (1 1/4 pound) cooked meat, chicken or beef (from making stock or broth)
To make the roux:
1 onion, chopped
60 gram (1/4 cup) butter
60 gram (1/2 cup) flour
1/2 liter (2 cups) stock
pepper,salt, mace, nutmeg to taste
For the breading:
flour
eggs or egg whites
toasted breadcrumbs

Preparation in advance: 
Chop the meat very finely. 
Make a roux with butter, flour and stock, but start with sauteing the onion. When the sauce is ready, add meat and spices. Let the ragout cool completely. Keep the ragout refrigerated until use, or freeze it.

Preparation:
Keep the ragout in the refrigerator until just before making the kroketten. Use your hands to form either sticks (about 10 by 3 cm/4 by 1.25 inches) or balls (diametre 4 cm/1.5 inches). Don't make them too large, or they'll have to be deepfried too long. If necessary, return the formed kroketten to the refrigerator.It is easier to bread them when they are cold.
For the breading, take three soup plates, put flour in one, stirred eggs or egg whites in the the second, and bread crumbs in the third plate. One by one, cover the kroketten with flour, then eggs, then bread crumbs. Mind that the kroketten are covered all over, otherwise the ragout may leek out when you deep fry them. Return the kroketten tio the refrigerator for thirty minutes.
Heat oil or whatever you use for deepfrying to 180dgC/355dgF. Fry the kroketten to a golden brown, about four minutes. Drain on paper towels.

To serve:
Serve them really hot. In the Netherlands they are eaten as snack or appetizer, or as the main course with french fries and apple sauce. Or serve them the old-fashioned way, as a first course.
Typpically Dutch too is serving mustard withbitterballen and kroketten. You can make that yourself too.

Variations: There are countless possibilities. Just remember one thing: 

sauce + stuffing = ragout, ragout + breading = kroket.

With this in mind you can make kroketten of almost anything. But the ragout must be well stuffed (for one decilitre of liquid use 110 gram stuffing), and thickened more then you would when making an ordinary ragout. 
Meat kroketten: You can use any soup meat (beef, chicken), but also veal or lamb, and lovely croquettes are made with sweetbread.
Creese kroketten: use milk in making the roux, cheese instead of meat, bring to taste with white pepper, nutmeg, parsley.
Fish kroketten: Use fish fumet, and herbs like dill or chives.
Game kroketten: For these you use a brown roux: Let the butter colour slightly before adding fl;our, keep the fire higher than when making a blond roux, sauté the butter/flour paste a little longer. Use more butter/flour than for a blond roux, 70 gram each for a half litre. Use good (game) stock for the sauce. Additions you can come up with yourself.
Vegetable kroketten: Make a blond roux with milk or vegetable stock, add blanched vegetables like asparagus, broccoli, peas). You can add some cheese, herbs, parsley. Mushroom kroketten are better with a ragout made with meat stock (or the liquid dried mushrooms have been steeped in).

The basics of making a roux: A roux is very easy to make. Just remember one thing: butter and flour have to be equal amounts in weight. What you make depends on how much liquid you add. If you make a soup, use thirty to fifty gram butter/flour for one litre, for making a sauce use forty to fifty gram butter/flour for a half litre, for a really thick sauce (like for kroketten), use sixty gram butter/flour for half a litre.
Start with melting the butter. Depending on whether you want your roux blond or brun, keep the butter light or heat a little longer. 
A blond  roux works best for soups and most simple sauces: Add all flour at once. Stir with a wooden spoon or a whisk until it has blended with the butter to a paste. Keep stirring on a low fire for a few minutes, without letting the paste colour. Now you start adding the liquid that can be either hot or cold. Begin with adding a very small amount of liquid (one tablespoon).  As soon as it hits the paste, the paste will become crumbly and turn dough-like. No panic, keep stirring until it is smooth again. Then add a little more liquid, stir until smooth again, more liquid, stir, stir, liquid, stir, stir, stir. The more liquid as already been absorbed, the more you can add in one go. But wait each time until the liquid has been completely absorbed, and the sauce is smooth again and has bubbled.
Variations: When the butter has melted, add a chopped onion or some garlic, or any herbs or spices that have to be heated (like curry powder). If you want to add bacon to the roux, take a little less butter because of the fat that will melt from the bacon (or fry the bacon in a separate skillet).
If you want to make a cheese sauce, make the roux with milk, and when all milk is added, then add grated cheese (or small cubes). You can use almost any cheese you like (Gouda, Stilton, Roquefort, Cheddar), but I find that very old/dry cheeses like Parmigiana Reggiano or old Pecorino are better combind with other cheeses.