1. Heat a large nonstick skillet over medium heat. Coat pan with cooking spray. Add onion to pan; cook 7 minutes, stirring occasionally. Add tomato and next 5 ingredients (through crushed red pepper); bring to a boil. Reduce heat, and simmer 10 minutes or until liquid almost evaporates. Add mussels; cover and cook 4 minutes or until shells open. Remove from heat; discard any unopened shells. Sprinkle with black pepper. Divide mussel mixture evenly among 8 shallow bowls. Sprinkle with feta and garnish with dill sprigs, if desired. Serve immediately.