Using a pre-made pesto makes this a dish that comes together fast! I like to serve this with a shaved fennel salad but some mixed greens dressed with olive oil and balsamic would be excellent as well.
Heat avocado oil in a hot pan over medium-high heat. Add the beef and cook until browned on all sides and cooked to your liking, about 7 minutes for medium rare (125ºF).
Remove from heat and stir in the pesto, tossing to coat the beef evenly.
Add the shaved fennel to a bowl and drizzle with olive oil and vinegar. Season to taste with salt and pepper.
Divide the fennel between two plates and serve with the beef along side.