Immersion blender method: In a tall jar, blend water, lemon juice, garlic, Dijon, dill, parsley, dates, capers with brine, and nutritional yeast. Add pumpkin seeds and blend until creamy. Season with salt and pepper.
Blender method: Add the water, lemon juice, garlic, Dijon, dill, parsley, dates, capers with brine, nutritional yeast, and pumpkin seeds to a high-speed blender. Blend on high until creamy. Season with salt and pepper.
Notes
Some mustards are stronger than others. I recommend starting with 2 teaspoons and adding more to taste, up to 3 teaspoons for a bolder flavor.
Fresh herbs - Substitute the parsley and dill with fresh herbs you have on hand.
Soak pumpkin seeds for 15 minutes if using a lower-power blender.
Add water or olive oil slowly to reach your preferred consistency.
Store leftovers up to 4 days, or freeze for up to 3 months.