1. Bring vinegar and sugar to a boil in a heavy saucepan, stirring until sugar dissolves. Reduce heat and simmer for 10 minutes. Remove from heat.
2. Add apples, lemon juice and salt to vinegar mixture. Simmer for 45 minutes, stirring frequently, until apples are tender and mixture has reduced to a glaze-like consistency. Cover and chill to hold.
3. Add basil just before serving and stir to blend.