Prep jalapeños: Remove stems and seeds (keep some seeds for more heat). Chop roughly.
Combine base: Add mayo, sour cream, and buttermilk to blender.
Add fresh ingredients: Add jalapeños, garlic, cilantro, parsley, and lime juice.
Add seasonings: Add dill, onion powder, garlic powder, cumin, salt, pepper, and cayenne.
Blend: Blend on high 30-60 seconds until completely smooth. Scrape down sides if needed.
Adjust: Check consistency. Add buttermilk to thin or mayo to thicken. Taste and adjust seasoning.
Chill: Transfer to airtight container. Refrigerate minimum 30 minutes for flavors to meld.
Serve: Stir before serving. Use as dip, dressing, or topping.