Dissolve the salt in 4 quarts of cold water in a large container. Add the chickpeas and soak at room temperature for at least 8 hours or up to 24 hours. Drain and rinse the chickpeas well before starting the stew.

Heat the oil in a Dutch oven over medium heat until it shimmers. Add the fennel, onion, and salt, and cook until the vegetables are softened and translucent, about 7 to 10 minutes.

Stir in the garlic, oregano, and pepper flakes and cook until fragrant, keeping the aromatics moving to prevent browning.

Stir in the water, broth, drained chickpeas, Parmesan rind, bay leaves, and orange zest and bring to a boil. Reduce the heat to a gentle simmer and cook until the chickpeas are completely tender, about 1 hour and 15 minutes to 1 hour and 45 minutes.

Stir in the escarole and tomato and cook until the escarole is wilted and tender, about 5 to 10 minutes.

Remove the pot from the heat and discard the bay leaves and Parmesan rind, making sure to scrape any cheese that has melted onto the rind back into the stew. Season with salt and pepper to taste. Serve in individual bowls topped with a sprinkle of Parmesan and a light drizzle of extra oil.