In a medium saucepan, whisk together the mustard, honey, apple cider vinegar, brown sugar, and ketchup until smooth.
Add the Spices
Stir in smoked paprika, garlic powder, onion powder, chili powder (if using), and a pinch of salt and pepper.
Simmer the Sauce
Place the saucepan over medium heat and bring the mixture to a gentle simmer, stirring frequently to avoid scorching. Let it simmer for about 8–10 minutes, allowing the flavors to meld and the sauce to thicken slightly.
Taste and Adjust
Taste your sauce and adjust the seasoning. If you prefer it sweeter, add a bit more honey. For tanginess, splash in a little more vinegar.
Cool and Store
Once the sauce has cooled, transfer it to an airtight jar or container. Store in the refrigerator for up to 2 weeks.