Tortilla de Riñones

trozo de tortilla de riñones

The Spanish Tortilla is typically a fat, cake like, omelette containing potatoes and sometimes onions. However, a tortilla can contain all sorts of ingredients, such as mushrooms, spinach, tomatoes and even bacalao (salt cod). I’ve enjoyed Tortilla de Riñones in the past, so when I cooked Riñones al Jerez last week, I deliberately included more kidneys than necessary, so that I’d have leftovers to make a Spanish omelette.


In the Oxford Companion to Food,  Alan Davidson suggests that the tortilla may have originated in Persia as kuku (a fried beaten egg cake containing herbs) and come to Spain with Sephardi Jews or the Moors. This might have arrived in Italy as a Frittata, via Sicily at a similar time. It’s also worth noting that the word omelette purportedly comes from the Roman dish overmele – a dish of eggs, honey and pepper, contained in the recipes of the epicure Apicius. Interestingly, there is a popular Persian kuku with potatoes, which illustrates how foods travel around the Mediterranean in circles. Potatoes first arrived in Europe via Spain, from the Americas, in 1492.

Tortilla de Riñones:

6 large eggs (beaten)
1 large onion (chopped)
6 pieces garlic (finely chopped)
2 lambs kidneys (chopped – leftover from riñones al jerez)
a heaped teaspoon chopped parsley
Sea salt and cracked black pepper (to taste)
lots of olive oil


The onion should be soft and sticky, so sofreír (poach slowly) in plenty of olive oil. A large volume (depth) of onion helps, there’s more water being released and this keeps it moist. Stir often and if you notice the onion drying out, add more olive oil. Do not cover with a lid – the liquid in the onion is supposed to evaporate.


When the onion looks right, melts on the tongue (almost) and tastes sweet  (20 – 30 minutes) add the chopped garlic.

riñones cortados

Stir in the chopped kidney, to warm it trough. These were two kidneys, previously cooked in sherry. If you don’t fancy kidneys, leave them out or substitute mushrooms. Do precook mushrooms first and allow their moisture to evaporate.

huevos y perejil

Beat 6 eggs and season with salt and pepper – the best way to check if the eggs have enough salt is to taste them raw. Stir the hot onion mixture into the beaten eggs and allow them to rest for 5 minutes – this prethickens the tortilla before you start to cook it. Add the parsley, just before frying the omelette.

aceite caliente

Pour a generous amount of olive oil into the frying pan and get it quite hot. You should see in rippling slightly and it should be on the verge of smoking. Swirl the oil around the pan, so that the sides are moistened and pour in the egg mixture. The hot oil will set the bottom and sides of the tortilla instantly. Shake, put a plate or lid over the top of the pan and turn the heat down. This allows the middle to set slightly.

tortilla volteada

When you smell caramelised egg, it’s time to flip the tortilla. Use a plate that is larger than the frying pan, place it over the top and in a single movement, turn the tortilla over and onto the plate. If in doubt, do this over the sink. You should have the tortilla, wet side down, sitting on the plate. Pour a little more oil into the pan, make sure it is hot and slide the tortilla back in, to cook the wet side. Turn the heat down immediately the egg hits the pan. Shake the pan backwards and forwards occasionally to stop the egg sticking.

tortilla de riñones

The tortilla can be flipped several more times, as necessary, to get a nice shape and colour. This can be cooked until it has set in the middle or it can have a runny centre. If necessary, poke a knife into the middle and have a look. Tortilla can be served hot or cold as a main course, it can be chopped into little pieces as a tapa and it’s commonly used as a sandwich filling (when sliced). It’s a normal sight to see people going to work at 7am with a long bocadillo de tortilla, wrapped in aluminium foil – a bocadillo is a sandwich made with a baguette. I like to eat tortillas with salsa brava, my guilty pleasure being that I prefer the cheap stuff (with a chilli kick), as opposed to the mild and delicate (posh) versions on sale. A glass of Fino makes a perfect accompaniment, especially with the hint of sherry in the kidneys.

the poacher

Tortillas are usually cooked on the hob and flipped. There are people who bake them in the oven, but IMHO that’s a frittata and scorching the top under the grill (broiler) drys them out too much for my liking.  I’ve cooked more tortillas than I can count and usually use cast iron frying pans of various sizes. My record (so far) is 28 eggs, using a very large chopping board for flipping. However, when I first arrived in Barcelona, I remember cooking the first couple of tortillas as being a bit daunting. Not long after moving to a new shared apartment, someone bought an egg poaching pan (like the one above). The cups and tray can be removed, the inside is nonstick, it’s quite deep, has a flat bottom and is about 8 inches (21cm) across – it holds a 6 egg tortilla perfectly, fits normal sized plates for flipping and is absolutely perfect for making tortillas!

About Mad Dog
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6 Responses to Tortilla de Riñones

  1. Eha says:

    Great fun ! You tend to make ‘tortillas’ which you flip over, I make endless ‘frittatas’ which I do finish under the grill to avoid the concoction on the floor during flipping 🙂 !! Mine tend to contain the fridge leftovers which oft amount to various mushrooms – the beauty of a kidney tortilla or frittata has so far eluded me . . . but . . . as soon as I can ! Yes, I have to cook my onion more slowly and follow your notes carefully and daresay have a more moist result – and, next time around I shall try and flip ! Shall report back . . .

    • Mad Dog says:

      Thanks Eha – I make both and there is a huge textural difference. I really like tortillas with soft sticky onions and a runny egg center, whereas a frittata is more set, like a quiche. There’s also a lot more olive oil in a tortilla.

  2. Ron says:

    I love making and eating Mexican omelets served with salsa so this is right up my alley. I’m now sitting here debating what I can put in your Spanish tortilla that I must now try. I don’t have the lamb kidneys but would love to try that one. We always get lamb hearts and liver from our lamb producer but I have never asked for the kidneys. I must ask when we get our spring lamb.
    However, I do have some fresh mushrooms, so I’ll try it with those. I love the idea of serving salsa bravas with the tortilla.
    A 28 egg flip is impressive indeed MD and is a feat I fear I could not master without cracking many eggs…

  3. Karen says:

    When we lived in the Miami area, there was a Spanish restaurant we used to visit that served a delicious potato tortilla that was served at room temperature.

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