Start by cutting the filet mignon into smaller pieces, just like in the video.
Season with a pinch of salt and black pepper, repeat the process on both sides of the meat and set aside.
In a frying pan, add a drizzle of olive oil, add the red onion chopped into thin strips, sauté.
Add the pepper cut into strips, the red pepper cut into small cubes and sauté again for 2 minutes.
Season with a pinch of salt and black pepper, mix.
Add balsamic vinegar and sugar, mix well. Add the chopped spinach, sauté one more time and set aside.
Now, in another pan, add a drizzle of olive oil, add the chopped meat and fry until golden.
Once done, add the rosemary sprigs, unsalted butter and crushed garlic cloves, sauté for 5 minutes.
Serve with peppers.