In a high speed blender, combine the cashews, water, lemon juice, Dijon mustard, sriracha, pimento peppers, garlic, smoked paprika, salt and a generous pinch of pepper. Blend until smooth, using the blender baton to help keep the blade moving. If the mixture is too thick, gradually add more water until smooth. Chill until ready to use. Garnish the dip with the chopped chives and serve with crackers, celery, and radishes for dipping.