In a small bowl, combine soy sauce, vinegar, and sugar. Season steak with salt. In a large skillet or wok, heat oil over high. Cook steak, undisturbed, until brown on one side, 2 minutes (do not overcrowd pan). Flip and cook until cooked through, 30 seconds. Transfer to a bowl.
Add asparagus, snap peas, garlic, and ginger to skillet. Cook, stirring constantly (add a little water if pan gets too dark), until vegetables are crisp-tender, about 4 minutes. Add soy mixture and cook until fragrant, about 10 seconds. Remove skillet from heat and stir in lemon juice and basil. Toss steak with vegetables; serve with rice and lemon wedges if desired.