Enjoy your Spanish omelette!

Making a Spanish omelette, also known as a "tortilla española" or "tortilla de patatas," is a delicious and classic Spanish dish. Here's a step-by-step recipe:

### Ingredients:
- 4-5 medium potatoes
- 1 medium onion (optional)
- 6 large eggs
- Olive oil (for frying)
- Salt

### Instructions:

1. **Prepare the Potatoes and Onions:**
- Peel the potatoes and cut them into thin slices (about 1/8 inch thick).
- Peel and thinly slice the onion, if using.

2. **Fry the Potatoes and Onions:**
- In a large frying pan, heat about 1/2 cup of olive oil over medium heat.
- Add the potato slices and onion slices to the pan, seasoning with a pinch of salt.
- Cook the potatoes and onions slowly, stirring occasionally, until the potatoes are tender but not browned (about 20-25 minutes).

3. **Drain the Potatoes and Onions:**
- Once the potatoes and onions are cooked, use a slotted spoon to transfer them to a large bowl. Let them cool slightly.
- Reserve the olive oil for later use.

4. **Prepare the Eggs:**
- In a separate large bowl, beat the eggs and season with a little salt.
- Gently mix the cooled potatoes and onions into the beaten eggs until well combined.

5. **Cook the Tortilla:**
- Heat a couple of tablespoons of the reserved olive oil in a non-stick frying pan over medium heat.
- Pour the egg, potato, and onion mixture into the pan, spreading it out evenly.
- Cook on medium-low heat until the edges start to set, and the bottom is golden brown (about 6-8 minutes).

6. **Flip the Tortilla:**
- Place a large plate over the pan and carefully invert the tortilla onto the plate.
- Add a little more reserved oil to the pan, then slide the tortilla back into the pan, uncooked side down.
- Cook for another 5-6 minutes until the tortilla is set and golden brown on both sides.

7. **Serve:**
- Slide the tortilla out of the pan onto a serving plate.
- Let it cool slightly before cutting into wedges.

### Tips:
- Use a good quality non-stick pan to make flipping easier.
- Some people prefer their tortilla a little runny in the middle. If so, adjust the cooking time accordingly.
- Serve warm or at room temperature. It can be eaten on its own or with a side of bread and a salad.