Prepare the onions, avocado dip, and beans as directed, in that order.
Once they’re ready, warm the tortillas in a large skillet over medium heat in batches, flipping to warm each side. Alternatively, you can warm them directly over a low flame on a gas range. Stack the warmed tortillas on a plate and cover with a tea towel to keep warm.
To assemble the tacos, spread refried beans down the center of each tortilla. Top with avocado dip and onions (for reference, I used all of the beans and about half of the avocado dip and onions). Finish the tacos with garnishes of your choice, and serve immediately.
Leftover components are best served separately; reheat the tortillas and beans before serving. Leftover pickled onions and avocado dip are great on quesadillas, nachos or tortilla chips, sandwiches, etc.