Chimichurri is a thick and flavorful herb sauce. Fresh basil and marjoram stand in for traditional parsley in this version of the Argentine favorite.
Heat oil in a small nonstick skillet over medium-high heat. Add shallots and garlic; sauté 3 minutes or until tender. Remove from heat; stir in juice, vinegar, and red pepper. Cool. Combine shallot mixture, arugula, basil, and marjoram in a small bowl. Stir in 1/4 teaspoon salt and 1/4 teaspoon black pepper. Set aside.
Combine paprika, remaining 1/2 teaspoon salt, and remaining 1/4 teaspoon black pepper. Rub paprika mixture over steak. Place steak on a grill rack coated with cooking spray; grill 6 minutes on each side or until desired degree of doneness. Let stand 5 minutes. Cut steak diagonally across grain into thin slices. Spoon sauce down center of slices, and serve.