In a large skillet over low heat, toast the pine nuts, stirring frequently until lightly browned. Remove the pine nuts and set aside. Wipe out the skillet.
Meanwhile, pour about ½ cup of hot water over the raisins and let them plump about 10 minutes. Drain and set aside.
Rinse the spinach thoroughly (do not dry it) and remove the tough stems. Increase the heat to medium and add the spinach, still wet from being rinsed, to the dry skillet. Turn as needed until all the spinach is wilted, 2 to 3 minutes. Transfer the spinach to a colander and let drain.
Remove any remaining water from the skillet and put the pan back on the heat. Add a thin layer of olive oil and when hot, add the onions and garlic. Cook stirring frequently until just starting to brown, 1 to 3 minutes. Add the spinach, raisins, and pine nuts and stir 1 to 2 minutes to warm through. Turn off the heat. Squeeze the juice from the ¼ lemon over the spinach mixture and stir in salt and pepper. Adjust seasoning as needed and add a little more lemon juice if the spinach tastes bitter.
Serve warm or room temperature.