1. Heat 2 teaspoons oil in a large nonstick skillet over medium heat. Add sliced fennel and cook, stirring occasionally, until lightly browned (5-6 minutes).
2. Stir in beans, tomatoes, and wine. Cook, stirring occasionally, until the tomatoes begin to break down (3-5 minutes). Transfer to a bowl; stir in chopped fennel fronds, mustard and 1/4 teaspoon pepper. Cover to keep warm.
3. Combine fennel seeds and the remaining pepper in a small bowl. Sprinkle evenly on both sides of salmon.
4. Wipe out the pan. Add the remaining oil to the pan and heat over high heat until shimmering. Add the salmon and cook until golden brown (3-5 minutes). Turn the salmon over, cover and remove from the heat. Let stand until the salmon finishes cooking off the heat, reaching an internal temperature of at least 145 degrees F (3-5 minutes).
5. Serve salmon warm on top of the warm bean mixture.