Rinse, stem, seed, and thinly slice peppers. Rinse lemon; trim ends and discard them. Thinly slice lemon and cut slices into quarters; discard seeds.
In a 4- to 5-quart pan, combine 1 cup water, peppers, lemon, vinegar, sugar, and aromatic spice mix. Bring to a boil over high heat and boil rapidly, stirring often, until liquid is almost evaporated, about 20 minutes; take care not to scorch. Serve warm or cool. Stir before serving.