In small bowl, mix soy sauce, oil, chopped thyme and oregano, garlic, honey and Sriracha sauce until well blended. Pour into large resealable food-storage plastic bag. Add pork; refrigerate at least 4 hours or up to 24 hours to marinate, turning occasionally.
Heat gas or charcoal grill. Remove pork from marinade; discard marinade. Place pork on grill over medium-high heat. Cover grill; cook 18 to 20 minutes, turning several times, until meat thermometer inserted in center reads 145°F. Cover; let stand 3 minutes before slicing. Garnish with thyme and oregano sprigs.