Begin by peeling and thinly slicing about 2 cups of shallots. In a skillet, heat 2 tablespoons of olive oil over medium-high heat. Once the oil is shimmering, add the sliced shallots, sautéing until they start to sizzle. Reduce the heat to low, stirring frequently for around 20 minutes, until the shallots are deep amber and meltingly tender. Transfer them to a paper towel to drain and sprinkle with flaky sea salt.

While the shallots are caramelizing, rinse and trim 2 pounds of fresh green beans, removing any tough ends. In a large mixing bowl, toss the green beans with a couple of tablespoons of olive oil and a generous pinch of sea salt until well-coated.

Preheat your oven to 450°F (230°C). Spread the seasoned green beans in a single layer on a baking sheet lined with parchment paper. Roast the green beans in the hot oven for 15 to 25 minutes, tossing halfway through.

After roasting, drizzle the green beans with vinegar to taste, adjusting seasoning with more salt if needed. Toss gently, transfer to a serving platter, and top with the caramelized shallots just before serving.