Ingredients:

a generous splash of olive oil or (3T.) knob of butter
3 small onions, chopped
a couple pinches of fine-grain sea salt
pinch of crushed red pepper flakes
3-inch sprig of rosemary
1 1/2 pounds yellow or green summer squash, cut into 1/2-inch thick slices/chunks
3/4 pound potatoes, un-peeled, cut into 1/4-inch thick pieces
3 medium cloves garlic, chopped
3 cups lightly flavored vegetable stock or water
2/3 cup buttermilk

garnish with: fresh herbs, toasted almonds, a generous drizzle of olive oil/ melted butter, and/or some crumbled feta

Heat olive oil/butter in large thick-bottomed pan over medium heat. Stir in the onions, salt, red pepper flakes, and rosemary. Saute until onions are tender - a couple minutes. Stir in the squash and potatoes, and cook until the squash starts to get a bit tender - a few minutes. Stir in the garlic, remove the sprig of rosemary, and then add the stock (or water) to the pot. Bring to a boil and then reduce the heat to a simmer, stirring occasionally until potatoes are tender, about 15 minutes.

Puree with a hand blender. If you like a silkier soup feel free to pour the soup through a strainer. Slowly whisk in the buttermilk, taste, and adjust the seasoning - adding more salt if needed. Top the soup with a bit of crumbled feta, some toasted almonds, a drizzle of olive oil, and a small pinch of red pepper - but it's perfectly good straight with no fuss on top.