In a large heavy saucepan, bring water and salt to a boil. Reduce heat to a gentle boil; slowly whisk in cornmeal. Stir in serrano pepper, garlic and pepper. Cook and stir with a wooden spoon for 12-17 minutes or until polenta is thickened and pulls away cleanly from the sides of the pan. Stir in cheese.
Spread into a greased 8-in. square baking dish. Cool slightly; cover and refrigerate for at least 4 hours.
For salsa, in a small bowl, combine the tomatoes, asparagus, green onions, cilantro, serrano pepper, salt and pepper; set aside.
Cut polenta into eight pieces. Moisten a paper towel with cooking oil; using long-handled tongs, lightly coat the grill rack. Grill, covered, over medium heat for 5-7 minutes on each side or until lightly browned. Serve with salsa; garnish with cheese if desired.
Wear disposable gloves when cutting hot peppers; the oils can burn skin. Avoid touching your face.