Crosshatch the filet to create plenty of surface contact. Preheat the griddle on high heat. Season the filet with Blackstone Steakhouse seasoning and Citrus Mojo seasoning.
Add a little avocado oil to the griddle and place the filet down. Press gently with your hand or a spatula to ensure good contact.
For the chimichurri, finely chop the parsley and cilantro. Add chopped red bell pepper, minced garlic, juice of half a lime, juice of one red grapefruit, salt, pepper, olive oil, and yuzu rice vinegar. Mix well.
Flip the filet occasionally, making sure to cook all sides, including the edges.
Once the filet is almost done, add butter, fresh thyme, rosemary, and minced garlic to the griddle. Baste the filet with the herb-infused butter, turning the herbs for extra flavor.
When the filet reaches your desired doneness (medium-rare recommended), remove it from the griddle and let it rest for 5 minutes.
Remove the herbs and garlic from the griddle and place them on a plate. Slice the rested filet and place it over the herbs.
Drizzle some of the herb-infused butter over the sliced filet and spoon the chimichurri over the top.
