1Combine the dill, vinegar, mustard, salt, and a pinch of black pepper in a small bowl. Stir to combine, then whisk in the oil until thick and emulsified. Set aside.
2Put the whole potatoes in a large sauce pan and cover generously with cold water. Add a big pinch of salt and bring to the boil over high heat. Reduce the heat so the water’s at a steady simmer, and cook until the potatoes are cooked but not falling apart (check by piercing a potato with the tip of a small knife), about 25 minutes. Drain and spread the potatoes out in a single layer to cool until they’re easy to work with, about 10 minutes.
3Cut the warm potatoes in half lengthwise and place in a large bowl along with the cucumber slices and red onion. Add the dressing, stir to coat well, and serve immediately.
Sweet potatoes are absolutely marvelous—they’re incredibly versatile, naturally sweet, loaded with nutrients and fiber, and low in calories. Really, what’s not to love? Here, they're simply sliced and cooked to make the perfect crust for a quiche.
Sweet Potato Casserole
This is not your mother's sweet potato casserole (and that's a good thing). This version is only lightly sweetened, tender rather than gloppy or mushy, and accented with a hint of ginger. It's still topped with browned, gooey marshmallows, though, because some traditions are worth sticking to.