Not sure whether you really want a true Belgian wit. But if you do:
- you DO need to have (unmalted) wheat. "wit" means "wheat". Maybe steep wheat flakes?
- you DO need coriander. It's the coriander that provides the citrusy flavor. The orange peel balances this out with its bitterness. The trick is to dose it correctly. I'd say order of magnitude of 0.75 gram per liter. Don't overdo it.
- you DO need witbier yeast, not Belgian Ardennes.
- you need to keep the IBUs low, maybe 15 or so.
- you DON'T put a slice of lemon in your glass. It's not classy.