How to Make It
Heat a grill to medium-high (450°). Put anchovies, garlic, lemon zest and juice, chile flakes, oil, and salt to taste in a blender and blend until smooth.
Put steaks on a rimmed baking sheet and coat all over with 5 tbsp. anchovy dressing. Set aside.
Toast almonds in a frying pan over medium heat, stirring or tossing often, until golden brown, 4 to 5 minutes. Meanwhile, slice celery very thinly on the diagonal and put in a large bowl.
Grill steaks, covered, turning once, 6 to 8 minutes total for medium-rare. Meanwhile, hold parsley bunch like a bouquet, turn it upside down, and whack off leaves with a sharp knife. Remove coarse stems and add leaves to celery.
Toss celery, parsley, and almonds with all but 1 tbsp. dressing. Drizzle steaks with remaining dressing and serve with salad.