Arrange a rack 5 inches from the broiler and heat to high. In a large bowl, stir together the peanut butter, ¼ cup hoisin sauce, the zest and juice of the limes and 3 tablespoons warm water. Finely grate 1 garlic clove into the mix, then season to taste with salt. To the bowl, add — but don’t stir — the slaw, cucumbers, a big pinch of salt, jalapeño, if using, and the herbs. Set aside.