Heat a large skillet over medium high heat. Add the olive oil and let heat for 10-20 seconds, until shimmering. Add onions to the pan and season with a little salt and pepper. Saute for 5-7 minutes, or until onions start to soften a bit. Cover pan and reduce heat to medium low. Cook, stirring occasionally for 45-60 minutes, or until onions are golden. (To speed up the caramelization process, add 1 cup of water to the pan and bring to a simmer. The water will evaporate leaving the onions very soft and they will caramelize in about half of the time.)
Meanwhile, place the pre-soaked cashews, water, vinegar or lemon juice, and a pinch of salt into a blender jar. Blend, stopping to scrape down sides as needed. If the mixture is too thick and chunky, add a little more water. It should be the consistency of yogurt or sour cream. Add the pumpkin puree, sage, and nutmeg. Blend again until very smooth.
Transfer to a serving bowl. Stir in the caramelized onions, reserving about 1/4 cup for the garnish on top. Taste and add more salt, if needed. Transfer to a serving bowl.
Top the dip with reserved onions, and a sprinkle with freshly grated nutmeg and freshly ground black pepper. Serve at room temperature or warmed up with Deep River Chips. (Recommended flavors: Original, Salt and Cracked Pepper, Rosemary and Olive Oil, Sea Salt Vinegar, Sour Cream and Onion, or Black Truffle.)