Pat the eye fillet dry with a paper towel and season both sides evenly with sea salt and black pepper.
Heat a grill pan or cast-iron skillet over medium-high heat and add the avocado oil.
Sear the steak for approximately 3-4 minutes per side for medium-rare, then transfer to a plate to rest for at least 5 minutes.
While the beef rests, whisk together the lime juice, fish sauce, coconut aminos, sesame oil, and red chili flakes in a small bowl to create the dressing.
In a large mixing bowl, combine the mixed greens, sliced cucumber, halved cherry tomatoes, thinly sliced red onion, cilantro, and mint leaves.
Drizzle half of the prepared dressing over the salad and toss gently to coat the leaves.
Thinly slice the rested eye fillet against the grain and arrange the slices over the salad.
Top with the remaining dressing and garnish with crushed peanuts for a final crunch.