To make chimichurri: In food processor, combine parsley, cilantro, onion and garlic until chopped. Add olive oil, lemon juice, water, salt and red pepper; process until fully combined.
To assemble tacos: In medium skillet over medium-high heat, cook chopped chuck roast 5 minutes. Remove from heat and mix in 1/2 cup chimichurri. In grill pan, char tortillas then fill evenly with meat, avocado, radishes and queso fresco. Serve with remaining chimichurri.
Notes
Nutritional information per serving: 410 calories; 24 g fat; 12 g carbohydrates; 366 mg sodium; 2 g fiber; 41 g protein; 1 g sugar.