How to Make It
In a large, shallow bowl, whisk the buttermilk with 2 tablespoons of the olive oil and season with salt and pepper.
In a large skillet, heat the remaining 2 tablespoons of olive oil. Add the chard stems and season with the Aleppo pepper, sumac and a generous pinch each of salt and pepper. Cook over moderately high heat, stirring occasionally, until the chard stems begin to soften, about 5 minutes.
Add the chard leaves and the garlic to the skillet. Cover and cook over moderately high heat, stirring once, until the leaves are tender and wilted, about 4 minutes. Season the chard with salt and pepper and let cool to room temperature.
Spoon the Swiss chard over the buttermilk. Squeeze the lemon half over the greens, drizzle with olive oil and serve.
An Aleppo pepper (pronounced Uh-LEPPO) is a dried ground pepper from Syria and Turkey. It's mildly spicy, tart and fruity.