Marinate Steak: Mix marinade ingredients. Coat steak and marinate 2+ hours or overnight. Pat dry before cooking.
Cook Steak: Sear steak in hot pan with oil for ~3 mins per side, flipping every minute. Rest 10–15 mins, then slice thinly against the grain.
Make Crema: Blend all crema ingredients until smooth. Salt to taste.
Make Salad: Whisk dressing. Toss with carrot, cucumber, herbs, and green onion.
Toast Brioche: Pan-fry buttered brioche until golden.
Assemble Toasts: Spread crema on brioche, top with steak, salad, and optional garnishes.