Toast bagels until just lightly browned on cut sides, 1 to 2 minutes. Remove and let cool slightly.
Combine cream cheese, sun-dried tomatoes, capers, dill, and scallion in a small bowl. For each sandwich, spread a layer of cream cheese mixture on each bagel half. Layer on 1 1/2 ounces of salmon and sprinkle with black pepper. Drape some field greens over the salmon and top with the other bagel half. Cut sandwich in half crosswise.
Tip: Wrap the sandwich in wax paper and take it with you on the go.