1) caramelize the sugar over medium heat 2) when sugar is browned whisk in OJ, vinegar and salt ( be careful ) 3) add zest and heat over medium heat until all caramel is dissolved ( about 10 min ) 4) melt 2T of butter over low heat and sprinkle in flour. cook flour until the rawness is gone 5) strain in the OJ mixture and whisk until combined 6) whisk in the last 2T of butter
serve over ice cream or crepes with powdered sugar.