Toss deli roast beef with coleslaw mix and a quick dressing for a dinner that's ready in minutes. Fried onions add a fun topper to the salad.
Place coleslaw mix in a large bowl. In a small, nonaluminum saucepan, bring vinegar, sugar, oil, and salt to a boil. Pour boiling dressing over coleslaw and toss to coat.
Cut beef crosswise into thick strips; toss with coleslaw. Add mint to salad and toss again.
Place a single layer of onion rings on a plate and microwave for 30 seconds until crisp. Top salad with crisp onion rings. Serve green sauce on the side to spice up individual portions, if desired.