You can buy the empanada wraps online (I use the Fargo brand) from Tom Hixson. They come frozen, so just defrost them fully in the fridge before using. Each pack contains 12-14 empanada wraps, which seems like a lot, but the empanadas are actually quite small so they will get eaten. I loved these warm, although they're great cold and tucked into lunch boxes instead of sandwiches or grabbing on the go. Don't be tempted to use shortcrust pastry or puff pastry for these, you really need the empanada pastry for best results, as it's thinner, flaky and more elastic than other pastries we commonly use in the UK. Oh, and as with pastry in general, it's less easy to work with once it warms up, so get on with filling your empanada wraps straight from the fridge.
Tuna and Olive Empanadas (Empanadas de Atún)
1 tbsp butter
1 small, finely chopped onion
1 tbsp plain flour
1 free-range egg yolk
salt and pepper
2 x 160g cans of tuna, drained
14 green olives, from a tin, cut in half
1 egg, beaten with a drop of milk
Gently fry the chopped onion, with a pinch of salt, in the tablespoon of butter until softened. You don't want any colour on the onion, just let it turn translucent. Sprinkle in the flour and stir with the onions for about 30 seconds. Gradually pour in the milk and stir well, so that it forms a creamy sauce. Take off the heat and quickly stir in the egg yolk to add richness to the sauce and thicken it. Stir well, and set to one side to cool slightly.
Next, fill the empanadas. Take one disc of pastry in your hand and dip your finger in the beaten egg. Run it along one half of the edge of the pastry. Now add a teaspoonful of the onion sauce to the centre of the disc and crumble in some tuna on top. Add in two olive halves and fold the empanada wrap over, pressing the edges together to seal, so you have a half-moon shape. Press the edges well, so you have a flap around the outside edge. Now you can crimp the pastry, folding it back on itself until the empanada is sealed.
Repeat with the rest of the empanadas and lay out on a sheet lined with greaseproof paper. Brush with the beaten egg and milk mixture and bake for 15 minutes at 200ºC.