In bowl, combine peach halves with oil and salt; gently turn to coat. Grill, cut-side down, on high heat for 1 min. Turn over and grill another 1 min. Remove from heat to cool.
Chop cooled peaches into 1/2-in. (1-cm) cubes. Mix with basil, green onion, honey and lemon juice. Reserve 1/2 of peach salsa to serve on side later.
Place whole salmon fillet (skin-side down) or portioned fillets on cedar plank; top with remaining peach salsa. Grill on medium heat, with lid closed, 10 to 15 min., or until fish begins to flake and flesh is opaque (internal temperature of 158°F/70°C). Lift lid periodically to check fish and plank don't scorch excessively. Spray any flare-ups with water mister.
Remove planked salmon from grill. Garnish with additional basil leaves. Serve with reserved peach salsa.