Steam the spinach until tender, then as much as possible squeeze out the excess liquid using a cheesecloth or clean tea towel, then dice the spinach as finely as possible.
In a pan, heat the olive oil, and then fry the onion until soft.
Throw in the walnuts, anchovies and fresh herbs and cook for another minute or two, making sure to keep stirring.
Stir in the spinach and allow the mixture to cool.
Using a rolling pin, pound the steaks to make them as thin as possible.
Pour the spinach mixture over the steaks and spread it over evenly.
Next, roll up the steaks tightly, trying not to let too much of the spinach mixture squeeze out.
Use string to tightly tie the rolls up.
Barbecue with the lid down until tender and remember to remove the string before serving!
Recipe by The Paleo Network at https://paleo.com.au/recipe-spinach-walnut-beef-rotolo/