Wasabi Salmon Sandwiches

fish: (shallot mixture does double duty for salad dressing and fish marinade)
1/3 c rice vinegar
1/4 c minced shallots
2 T brown sugar
2 T minced peeled fresh ginger
1 T minced garlic (about 3 cloves)
3 T low-sodium soy sauce
1 1/2 t wasabi paste
4 (6 oz) salmon fillets (about 1"thick) skinned

Ginger-Garlic Mayonnaise:
2 T low-fat mayo
2 T plain fat-free yogurt
1t wasabi paste
3/4 grated peeled fresh ginger
1/2 t rice vinegar
1 garlic clove, minced

remaining ingredients:
1 T dark sesame oil
4 c baby spinah leaves
8 (1 oz) slices ciabatta bread, toasted

1. To prepare fish, combine first seven ingredients. Place 3/4 c shallot mix in large baggie. Set remaining mix aside. Add fish to bag; seal and marinate in refrigerator 30 minutes, turning once.
2. To prepare mayo, combine mayo and next 5 ingredients (through garlic clove).
3. Preheat broiler. (I George Foreman mine with foil for easy clean up)
4. Remove fish from bag; discard shallot mix in bag. Place fish on broiler pan; broil 10 minutes or until fish flakes easily with fork.
5. Combine the reserved shallot mix and dark sesame oil in a large bowl. Add spinach, toss well.
6. Spread about 1 T mayo on each of 4 slices of bread; top with 1 fillet. Top each fillet with about 1 c spinach mix; top with remaining bread slices.