Heat 2 tbs oil in a large nonstick skillet over medium heat.
Add sliced fennel; cook, stirring occasionally, until lightly browned, about 6 minutes.
Stir in beans, tomatoes and wine.
Cook, stirring occasionally, until the tomatoes begin to break down, about 3 minutes.
Transfer to a bowl; stir in chopped fennel fronds, mustard and 1/4 tbs pepper and cover to keep warm.
Meanwhile, combine fennel seeds and the remaining 1/4 tbs pepper in a small bowl; sprinkle evenly on both sides of salmon.
Wipe out the pan.
Add the remaining 3 tbs oil to the pan and heat over high heat until shimmering but not smoking.
Add the salmon, skinned-side up, and cook until golden brown, 3 to 5 minutes.
Turn the salmon over, cover and remove from the heat.
Let stand until the salmon finishes cooking off the heat, 3 to 5 minutes more.
Transfer the salmon to a cutting board and flake with a fork.
Serve salmon on top of the warm bean mixture.
Ready in 40 minutes.