Creamy butter beans tossed with sumac-pickled red onions, crisp cucumber, fluffy parsley, and briny feta in a bright red wine vinaigrette—fresh, tangy, and deeply satisfying in just 15 minutes.
In a large bowl, whisk together 1/4 cup extra virgin olive oil, 3 tablespoons red wine vinegar, 2 teaspoons sumac, 1 teaspoon dried oregano, 1 teaspoon honey, and 1/4 to 1/2 teaspoon fine sea salt.
Add 1/2 cup thinly sliced red onions to the dressing, toss to coat, and set aside for at least 10 minutes to soften and quick-pickle.
Finely chop the English cucumber into 1/4-inch (1 cm) cubes and finely chop the curly parsley (to make a tightly packed 1 cup).
Add the drained and rinsed butter beans to the bowl with the onions and dressing; toss well to coat. Add the chopped cucumber, parsley, and crumbled feta; toss gently to combine. Taste and adjust seasoning as needed.
Optional serving: Spread plain Greek yogurt on plates, drizzle with olive oil and a pinch of sumac, then spoon the salad on top.