In a large saute pan over medium-high heat, add the canola oil and heat. Add the onion, garlic and ginger and saute, stirring, for 1 minute. Add the cabbage and cook until just starting to wilt, about 2 minutes. Add the soy sauce and rice vinegar and stir well and cook just until cabbage is wilted, about 3 minutes. Remove from heat and drizzle with the sesame oil.