Jaccard each steak 10–12 times (or poke with fork 30–40 times). Cut into 4 equal pieces. Season both sides generously with salt; rest 15 min.
Combine all marinade ingredients; blend 30 s to a smooth paste.
Add steaks to a ziplock bag, add marinade, coat well, expel air, and seal. Chill overnight (or minimum 2 h).
To make the pico de gallo, dice tomatoes (discard pith/gel), place in strainer to remove excess tomato water. Combine tomato, onion, jalapeño, cilantro, lime juice & salt; stir. Let sit 20 min for flavors to mingle.
To make the tortilla dough, pulse flour, salt & butter to gravel in a food processor. Stream in water until a shaggy dough forms. Knead 2 min to a soft, cohesive ball.
Divide dough into 12 × 40 g pieces; roll into balls. Cover with damp towel 5 min. Roll each to a 7 in (18 cm) round, dusting lightly with flour.
To cook tortillas, cook in griddle or nonstick pan over medium heat: first side ~90 s until bubbles form, flip and cook another 30 s. Keep finished tortillas wrapped in warmer.
To grill the steaks, heat grill to high; oil grates well. Grill steak 3–4 min per side until lacquered and the internal temp reads 130–140 °F (54–60 °C). Rest 5–10 min.
Slice steak across the grain, then into ½-inch cubes.
To build the tacos, re-warm tortillas if needed. Spread mashed avocado, load with steak, top with drained pico. Fold and devour immediately—best carne asada tacos, period.