Heat nonstick 12-inch skillet over medium-high heat; add beef, potato, onion, garlic and jalapeño, stirring to break up beef. Cook 8 to 10 minutes or until beef is thoroughly cooked and potatoes are tender when pierced with tip of a knife. Remove from heat; drain, and pour beef mixture into ungreased 2-quart baking dish or shallow pan with sides. Stir in tomatoes, pepper flakes and 1 teaspoon salt. Refrigerate uncovered 10 minutes to cool.