Trim fat from beef. Combine tenderloin, green onions, and next 4 ingredients (green onions through garlic) in a large zip-top plastic bag; seal. Marinate in refrigerator 3 hours, turning occasionally.
Preheat oven to 450°.
Combine coriander and 1/4 cup pepper in a small bowl; set aside. Remove tenderloin from bag; pat dry with a paper towel. Discard marinade. Rub coriander mixture evenly over tenderloin. Place tenderloin on a broiler pan coated with cooking spray. Insert meat thermometer into thickest portion of tenderloin. Bake at 450° for 20 minutes or until thermometer registers 145° (medium-rare) to 160° (medium). Place tenderloin on a platter; cover with foil. Let stand 10 minutes. Slice tenderloin diagonally across grain into 12 slices; set aside.
Combine parsley and next 7 ingredients (parsley through garlic) in a large bowl. Add tomato slices; toss gently to coat. Place 2 tomato slices on toast; top with 1 slice of tenderloin and 1 tablespoon Miso Mustard Sauce.