Mint jelly is a classic accompaniment to lamb and is particularly well suited to the simple flavors of Roasted Leg of Lamb.
Blend mint and the water in the jar of a blender until mint is finely chopped. Transfer to a saucepan; bring to a boil. Remove from heat; let steep 45 minutes. Strain mixture through a fine mesh sieve into bowl; reserve liquid (1 3/4 to 2 cups). Discard mint.
Return liquid to saucepan; add lemon juice and sugar. Bring to a boil; cook 1 minute. Add pectin, and return to a boil; cook 1 minute. Remove from heat; stir in food coloring. Skim surface. Transfer to a large container; let cool completely. Cover; let chill overnight. Transfer to a serving dish, or store in refrigerator for up to 5 days.