While I personally don't like to corrupt the pure taste of spinach by adding onions, the dish is traditionally made with sauteed onions, so I have both options here.  Sprinkling a little Aleppo pepper and dried mint on the garlic yogurt adds a bit of color and depth to the dish.
Ingredients:
2 bunches of purslane or spinach, washed, dried and roughly chopped
2 tbsp. extra virgin olive oil
1 small yellow or white onion, diced (optional)
1 cupsfull fat traditional thick yogurt
1-2 garlic cloves
pinch of sugar
1/4 teaspoon salt and salt to taste
1/2 teaspoon Aleppo pepper (optional)
1/2 teaspoon dried mint, crumbled (optional)
Directions:
If using onions:  Heat a medium-sized pot or deep skillet over medium heat and add olive oil.  After two minutes, add the onions and saute until soft and translucent.  
If not using onions:  Heat a medium-sized pot or deep skillet over medium heat and add olive oil and heat for two minutes.
For both recipes:  Add the spinach or purslane and the sugar and saute until wilted but do not overcook!  Taste it after 3-4 minutes.  Everyone likes their greens cooked to varying degrees but I think the less cooking the better when it comes to this dish.  
To make the garlic yogurt:  make paste of the garlic and 1/4 teaspoon salt in a mortar and pestle.  Mix into the yogurt.  Taste the yogurt to make sure that the taste of garlic is not overwhelming -- you can always moderate by adding extra yogurt.  
Spoon the spinach into a bowl, drizzle the garlic yogurt on top, and then sprinkle with Aleppo pepper and dried mint, if you like.  Add salt to taste.