1 pound beef tenderloin (silverskin and fat removed, cut into 1-inch cubes)
1/4 cup canola oil (divided)
4 teaspoons Sugar (divided)
1 teaspoon Freshly ground black pepper
3 cups broccoli florets
1/4 cup low-sodium soy sauce
2 tablespoons fresh lime juice
1 tablespoon unseasoned rice vinegar
1 tablespoon fish sauce
1 teaspoon peeled, finely grated ginger root
1 clove garlic (peeled and very finely minced)
4 scallions (cut on the bias into 1/2-inch pieces)
2 tablespoons unsalted butter (divided)