Cook the macaroni in well-salted water according to package directions until just tender. Drain, rinse with cold water, and let cool completely.
In a large bowl, whisk together the mayonnaise, sour cream, mustard, lime juice, salt, and pepper until smooth.
Add the cooled macaroni, diced ham, corn, red onion, and jalapeños (if using).
Stir gently until everything is evenly coated. Add jalapeño juice for extra tang if desired.
Taste and adjust seasoning.
Cover and refrigerate for at least 1 hour before serving.
Garnish with cilantro if desired and serve chilled.