1/2 cup olive oil, plus more as needed
2 pounds (2 heads) broccoli, separated into small florets, stems peeled and diced
2 1/2 teaspoons kosher salt, more to taste
2 tablespoons unsalted butter
1 large spanish onion, diced
5 cloves garlic, chopped
1/2 teaspoon black pepper, more for finishing
1/4 teaspoon red pepper flakes
1/2 pound potato, peeled, and thinly sliced
1/4 teaspoon finely grated lemon zest
1 1/2 tablespoons fresh lemon juice, more to taste
grated or shaved parmesan, to finish (optional)
flaky sea salt, to finish
In a large soup pot, heat 2 tablespoons of oil over high heat. Add about a third of the broccoli, just enough so that it covers the bottom of the pan in a single layer without overcrowding.
Cook broccoli without moving it for about 3 to 4 minutes, or until dark brown on 1 side only (leave the other side bright green).
Transfer to a big bowl and repeat with remaining broccoli and more oil. When all the broccoli has been browned, season with 1 teaspoon salt and set aside.
Reduce heat to medium-low. Add butter and remaining 2 tablespoons of oil to pan. Add onions and garlic, black and red peppers, and 1/2 teaspoon salt.
Cook onion-garlic mixture until soft and translucent, about 4 minutes.
Add potato to the pot with 1 quart water and remaining 1 teaspoon salt. Bring to a simmer, cover pot and cook until potato is just tender, 10 to 15 minutes.
Add broccoli, cover again and cook until tender, another 5 to 10 minutes.
Add lemon zest and roughly purée soup with an immersion or regular blender, leaving some small chunks for texture.
Stir in lemon juice. Finish with grated Parmesan, a drizzle of olive oil, black pepper and flaky sea salt.
Andrew Feinberg of Franny’s restaurant in Brooklyn
Instead of merely boiling the broccoli to cook it, here, the florets are seared until deeply browned on one side while remaining bright green on the other. This gives the soup a layer of caramelized flavor while also preserving the fresh green taste of the broccoli itself.
