This delicately flavor-balanced cheesecake is just the right combination of rich creaminess and bright zestiness. Each mouthful presents a medley of sweet, sour, cream, and lime, and envelops your mouth with that decadent richness for which cheesecake is notorious.   Key Lime Cheesecake Ingredients CRUST 1 3/4 cups graham cracker crumbs 1/4 cup