To make the dressing, whisk all the ingredients in a medium serving bowl until blended.
For the salad, discard the ramen seasoning packet. Crush the ramen in the bag into very small pieces with a heavy skillet or your hands. Add them to the bowl with the dressing and toss to coat. Let the ramen stand at room temperature, stirring now and then, until the liquid is mostly absorbed, about 45 minutes.
Gently fold in the snow peas, carrots, scallion, and water chestnuts. Fold in the oranges and then scatter on the almonds and sesame seeds. Serve at room temperature or refrigerate for up to 2 days and serve cold.
Tip: Save time by replacing the dressing with store-bought light sesame-ginger dressing.