To make the dressing, combine the mustard, lime zest and juice, garlic, sumac, and Aleppo, and a good dash of kosher salt and black pepper in a small mixing bowl. Whisk, and while whisking vigorously, drizzle in ⅓ cup extra virgin olive oil, until emulsified.
In a large bowl, combine the beans, sardines, tomatoes, onions, jalapenos, and parsley. Toss gently to combine.
Pour the dressing over the salad and toss to combine. Taste and adjust seasoning to your liking.
