In a medium mixing bowl, whisk yogurt until creamy; stir in grated cucumber, mint, marmalade and cumin seeds if using.

Taste sauce, then add any or all of the optional seasonings, as desired. Transfer sauce to a serving bowl, cover with plastic wrap and refrigerate until needed. Stir before serving. (Raita can be prepared one day before serving.)

Note:
To roast cumin seeds, place seeds in a hot frying pan and cook for 2 - 3 minutes over medium-high heat until they begin to turn brown. Let seeds cool on a paper towel.