Add the ingredients for the chipotle cashew cream sauce to a blender or food processor and process until completely smooth - you may need to stop the blender and scrape the sides a few times. Transfer to a jar and refrigerate until ready to use. Note: the sauce will thicken in the refrigerator.
Prepare the Quesadillas:
Mash the avocados in a bowl and sprinkle with sea salt to taste.
Preheat the grill to medium high. Brush all of the vegetables with olive oil and sprinkle with sea salt.
Place the vegetables on the hot grill and cover. Cook for 5 to 8 minutes, flip and continue grilling another 5 to 8 minutes, or until charred and soft. Transfer vegetables to a cutting board and chop into bite sizes.
Heat a large skillet to medium-high and add enough oil to lightly coat the surface.
Place one large flour tortilla on the hot skillet and spread half of the mashed avocado mixture over the whole tortilla. Cook for about 30 seconds to 1 minute.
Layer a generous amount of vegetables over half of the tortilla, then fold tortilla in half. continue cooking until tortilla reaches desired level of crisp. Transfer to a cutting board and chop into pieces. Repeat for remaining ingredients.
Serve quesadillas with chipotle cashew cream sauce and chopped green onion.