Spread the beans out and pick through them, discarding any rocks, bits of debris, and shriveled beans. Rinse the beans under cold water to remove any dust or dirt. Put the beans in a large metal bowl with enough cool water to cover by about 3 inches. Soak at room temperature for 6 to 8 hours, adding more water if the level gets low. To see if the beans have soaked long enough, cut one in half. It should be the same color at its center as it is at the edge. Drain and rinse.
Tip:A long soak is the best way to ensure even cooking of the beans, but if you're short on time, you can do a quick soak in lieu of the step above: Put the beans in a large pot with enough cool water to cover by about 3 inches. Bring to a boil; boil for 2 minutes. Remove from the heat, cover, and let stand for 1 to 2 hours. Drain and rinse.
Put the beans in a heavy-duty 4-quart saucepan. Add 6 cups cool water, or enough to cover the beans by about 1-inch. Bring just to a boil over medium-high heat, reduce the heat to maintain a gentle simmer, and cook, partially covered, stirring occasionally and adding hot water if necessary to keep the beans submerged, until they begin to soften, about 30 minutes.
Add 1/4 tsp. salt and continue to cook, partially covered, until tender but still firm to the bite, another 15 to 20 minutes. Drain the beans in a colander and let cool to room temperature.
Finely grate the zest of the lemon to yield 3/4 tsp. and then squeeze it to yield 3 Tbs. juice. In a large bowl, whisk the lemon zest and juice, oil, shallot, garlic, coriander, 1/4 tsp. salt, and 1/4 tsp. pepper. Add the beans, toss to combine, and let sit at room temperature for at least 15 minutes and up to 2 hours.
Put the salmon skin side down on a plate. Season with 1/4 tsp. salt and 1/4 tsp. pepper, turn the salmon over, and let sit at room temperature for 15 minutes.
Meanwhile, position an oven rack about 4 inches from the broiler and heat the broiler on high. Cover the top of a broiler pan with aluminum foil.
Broil the salmon skin side up until just opaque throughout, 5 to 7 minutes. The skin will become blackened. Transfer to a cutting board and let cool to room temperature. Remove and discard the skin and break the flesh into 1-inch pieces with your hands.
Season the beans to taste with salt and pepper. Add the salmon, spinach, radicchio, and dill to the bean mixture, toss, and serve.
Serve with warm crusty bread for a hearty lunch or light dinner.