Decide what you need most: dry mustard spice (use mustard powder/yellow mustard powder) or tang + moisture (use Dijon or yellow prepared mustard).
Use the listed ratio, then mix thoroughly into the sauce, marinade, or dry rub base so the flavor blooms evenly.
If using prepared mustard, reduce slightly (start at the lower ratio) and adjust recipe liquid as needed for the correct thickness.
Taste after mixing (before final cooking if possible). Add small pinches only—ground mustard can turn bitter when overdone.
For heat control, separate “mustardy bite” from “background tang”: increase mustardy spice with powder swaps, but use prepared mustard in smaller increments.