Make the marinade: Whisk all ingredients together in a large bowl.
Marinate steak: Place steak into the marinade mixture; toss to coat the steak in the marinade. Cover bowl and place in refrigerator. Let steak marinade for 30 minutes or up to 12 hours.
Prep the ingredients per the instructions above.
Make the sauce: Place all ingredients in a blender, and pulse until blended well. Add more oil if needed for a smooth consistency.
Make the guacamole: Mash the avocado with a fork until it is smooth. Stir in the cilantro, garlic, and sour cream. Season with salt and pepper to taste. Sprinkle with smoked paprika.
Make the agua fresca: mix all ingredients together. Refrigerate until ready to serve. Serve over ice if desired.
Heat a grill or grill pan on medium heat.
Cook steak: Grill the steak on both sides until it reaches your desired temperature (see below). Set the steak aside to rest for 5 minutes before slicing thin against the grain.
Lightly grill the tortilla shells on each side to warm.
Serve: Layer the tortilla shells with arugula, steak, tomato, onion, and jalapeno then drizzle with sauce. Enjoy with lime wedges, chips, guacamole, and agua fresca.