In a small skillet over medium heat, dry roast pepper, garlic, coriander and mustard seeds until just aromatic or the seeds start to pop. This will take 1 to 3 min.; stir constantly. Immediately transfer to a small bowl to stop the cooking and avoid burning. Transfer roasted spices to a spice or coffee grinder and grind into a coarse powder. Place ground spices in a medium bowl. Add the mayo and yogurt and stir to incorporate the spices thoroughly. Stir in the remaining ingredients until smooth. Chill before serving.
Serve chilled over salad, as a dip for your favorite wings, or alongside veggie platter.