ABOUT THIS RECIPEFrom Tender Baby Potatoes to Crispy Edges
This salad gets its character from the contrast between the soft insides of the potatoes and their crisp, golden-brown outsides. Gently smashing small potatoes after boiling creates more surface area to brown in the oven. Use baby potatoes or other small waxy potatoes of roughly the same size so they cook at the same time. You can leave the skins on: they help the potatoes hold together and turn deliciously firm as they bake.
Boil the potatoes until a knife slides in with slight resistance; potatoes cooked until completely soft are more likely to fall apart when smashed. After draining, let them steam dry briefly, then gently flatten them with the bottom of a glass or a potato masher. They don't all need to be perfectly round. Bake them spaced apart on a hot baking sheet so moisture can escape and the edges brown rather than steam. You can also use a frying pan, but cook the potatoes in batches and turn them carefully.
The dressing is deliberately sharp and savory. Capers bring salty, floral notes, while mustard emulsifies the oil and lemon juice into a dressing that clings to the warm potatoes. Taste before adding extra salt: the capers and salted cooking water already add plenty of flavor. Use capers in brine or salt; rinse salt-packed capers first and pat them dry. No fresh lemon on hand? A mild white wine vinegar can replace the juice, though the flavor will be a little less fruity.
Toss the dressing with the potatoes as soon as they come out of the oven, but add the radishes and dill just before serving. That way, the slices stay fresh and crisp and the dill keeps its fragrance. The warm potatoes soak up more dressing, but gradually lose some of their crispness once tossed; serve the salad straight away for the best combination of textures. It goes well with roast chicken, fried fish or a vegetable tart, and can also round out lunch alongside a green salad. Store leftovers covered in the refrigerator and eat within two days; for better texture, reheat them in the oven, not the microwave.