Heat the olive oil in a Dutch oven over medium-high heat until the oil should shimmer but not smoke. Add the onions and salt and cook, stirring frequently, until the onions are softened and lightly browned, 5 to 7 minutes. Stir in the garlic and red pepper flakes and cook until fragrant.

Stir in the escarole, beans, broth, and water. Cook, stirring often, until the escarole is completely wilted, about 5 minutes.

Increase the heat to high and cook until the liquid is nearly evaporated, 10 to 15 minutes. The greens should be tender and the liquid should just glaze the beans.

Remove from the heat and stir in the lemon juice. Drizzle with the additional olive oil and season with salt and pepper to taste. Serve warm.