
Gather and prepare all ingredients.
Bring a large pot of water with 1 Tbsp salt to a boil. Once boiling, add the green beans and cook for 2 minutes. Drain and rinse the beans. Then set them aside.
In a small bowl, whisk together the lemon juice, zest, apple cider vinegar, Dijon, sugar, 1 tsp of salt, and pepper. While whisking, slowly pour in the oil until combined.
Place the green beans, onions, tomatoes, and feta in a bowl. Drizzle with the vinaigrette and toss to combine. Let it sit for 5-10 minutes, then serve, or refrigerate until ready.