In large saucepan, bring red wine vinegar and sugar to boil over medium-high heat. Boil until reduced to 1/2 cup, about 10 minutes, watching carefully. Whisk in olive oil.
Meanwhile, cook beans in a large pot of boiling salted water until just tender, stirring occasionally, about 5 minutes. Drain.
Pour vinegar mixture into same pot and return to simmer, whisking constantly. Return beans to pot and toss to coat. Season to taste with salt and pepper.
Transfer beans to bowl and sprinkle with almonds, if desired. Serve.
Prep Time: 5 mins
Cook Time: 20 mins
Total Time: 25 mins