Heat oven to 400°F. Cut four 15-inch rounds of parchment paper. Fold each in half; unfold. Lightly brush 1/2 teaspoon oil onto each parchment round to within 1 inch of edge.
Arrange potato slices evenly on half of each parchment round. Sprinkle with half of the salt and pepper. Top each with salmon; sprinkle with remaining salt and pepper. Top each with carrots, tomatoes and 2 herb sprigs.
To seal each packet, fold untopped side of parchment round over topped side. Fold open edge over several times, folding and twisting until packet is completely sealed. Place packets on ungreased cookie sheet.
Bake at 400°F. for 15 to 20 minutes, depending on thickness of fillets. Carefully unwrap 1 packet to check if fish flakes easily with fork; re-wrap and continue baking if not done.
Remove packets from oven; let stand 5 minutes before serving. Place packets on individual serving plates. Cut X-shaped slit in top of each packet; carefully tear back paper to serve.