Place wood chips in a bowl; cover with several inches of cold water and let soak for at least 1 hour.
Preheat an outdoor charcoal grill for medium heat and lightly oil the grate. Sprinkle wood chips over coals and close grill lid, leaving top vents open. When smoke rises from the vents, shut them, open the grill, and place fennel slices directly on the grates to create a bed.
Generously season salmon fillets with salt and black pepper. Place salmon on top of fennel slices. Close the grill lid, leaving the vents shut. Cook until salmon is tender and starting to flake, 15 to 20 minutes. Remove from grill and let rest for 5 minutes. Scrape fennel from the grill and place atop salmon while it rests or discard it (see Editor’s Note).
Combine tomatoes, olive oil, lemon juice, fennel fronds, sugar, salt, and black pepper in a bowl. Spoon tomato mixture over salmon and serve.