¼ cup white miso paste (see Note above) 2 teaspoons rice wine vinegar, plus more to taste 4 teaspoons honey, plus more to taste ¾ cup vegetable oil Up to 1 tablespoon water Combine the egg yolk, miso paste, vinegar, and honey in a tall narrow cup that will just fit the head of your immersion blender Carefully pour in the oil, so that it floats on top of the other ingredients Insert the blender into the bottom of the cup, turn on the blender, and slowly draw the head up through the oil: a thick emulsion should form as you do so Transfer the mayonnaise to a bowl and whisk in more vinegar and honey to taste Add up to 1 tablespoon water to thin the sauce to the desired consistency It should be thick and cling to your finger or a spoon but not feel pasty or waxy on your tongue HOW TO PREPARE COMMON TEMPURA INGREDIENTS INGREDIENT PREPARATION Green Beans Trim the ends Mushrooms Clean and thinly slice, or leave thin mushrooms like shiitake or oyster whole Bell Peppers Cut into ½-inch-wide rings or strips Zucchini and Summer Squash Cut into ½-inch rounds or sticks Onions Cut into ẵ-inch rings Eggplant Cut into ẵ-inch rounds Sweet Potatoes Peel and cut into ẳinch slices Butternut Peel, seed, and cut