1. Mix all the ingredients for the steak marinade and let steak soak in it for at least 30 minutes or overnight.
2. Process all the ingredients for the chimichurri in a food processor until smooth, set aside.
3. Heat a grill to high.
4. Cook steaks for about 3 minutes on each side until the steak is a medium rare. Set aside to rest for about 10 minutes.
5. While steak is resting, put the flour tortillas on the grill for about 30 seconds on each side until they are lightly charred.
6. Slice the steak thinly across the grain. Assemble the tacos by dividing the meat between the 8 tortillas. Drizzle about 1/2 a teaspoon of chimichurri over the meat. Top each taco with cheese, sliced radishes and pea shoots.