Marinating the steak: Combine all marinade ingredients in a large zip-top bag, add the steak, and seal tightly. Refrigerate for 2-8 hours.
Cooking the steak: Preheat grill to medium-high. Remove steak from marinade and grill to medium-rare, about 130°F, turning once. Rest for 5 minutes, then slice thinly against the grain.
Making the cilantro vinaigrette: Whisk all vinaigrette ingredients in a small bowl.
Preparing the Pico de Gallo: Combine all ingredients and let sit to merge flavors.
Assembling tacos: Fill taco shells with steak, top with Pico de Gallo and drizzle with cilantro vinaigrette.