Bring a large pot of salted water to a boil.

Meanwhile, make the vinaigrette. In a medium bowl, whisk together the grated garlic, sumac, and lemon juice. Slowly, while whisking, add in the sesame oil and olive oil until emulsified. Season with Kosher salt and freshly ground black pepper.

Heat a small pan over medium heat. Add sesame seeds and toast, stirring occasionally, until toasted, 2-3 minutes. Set aside until ready to use.

When ready to cook the green beans, prepare an ice bath with a large bowl of cold water and ice. Add green beans to the pot of boiling water and cook just until tender, about 3-4 minutes (cook on the longer side if serving room temperature). Drain and immediately transfer beans to ice bath. Let sit for a couple minutes to cool properly, then drain and dry with a paper towel. At this point they can be kept in an airtight container in the refrigerator until ready to dress and serve.

If eating immediately at room temperature, toss the green beans with the sumac vinaigrette and toasted sesame seeds. Taste and season with Kosher salt and freshly ground black pepper.