Fill a medium pot with water and stir in 1 tablespoon of sea salt. Set the pot on high heat and add the potatoes, leaving the unpeeled potatoes whole if small, or peel and cut larger potatoes in chunks if preferred. Boil the potatoes until almost fork tender.
Add the green beans and boil for a final 2 minutes - if your green beans are quite thick or fibrous add them for a final 3 minutes. Drain the potatoes and green beans and set aside to cool - the residual heat will soften up the green beans a bit further so don’t worry if they are a touch too crisp at this point.
Using the same pot filled again with fresh water (without salt), add the corn cobs and bring to a boil over high heat, cooking for 7-10 minutes depending on how toothsome you prefer your corn. Drain the corn and set the cobs aside to cool. It’s ok if the vegetables are still a bit warm once you begin to assemble the salad.
While the vegetables are cooling, make the feta cream. Add the feta, labneh or Greek yogurt, and minced garlic to the bowl of a food processor, mini chopper, or bullet style blender and blend until quite smooth. Alternatively, if you don’t have any of these appliances, you can place the ingredients in a bowl and hand mash/mix. Add the lemon zest to the smooth mixture and gently incorporate with a flexible kitchen spatula as you scrape the mixture out onto your serving platter, making gentle mounds around the bottom and sides of the bowl.
Finely chop the leaves, fronds and stems of the herbs. Add into a large mixing bowl along with the olive oil and the lemon juice. Mix well, taste and add salt as needed, remembering that the feta cream will be somewhat salty.
Use a corn zipper or knife to cut the corn kernels off of the cob, and place the cooled corn kernels, potatoes, and beans into the same bowl with the herb mixture and mix well.
Mound the vegetable salad onto the feta cream, sprinkle with the nigella seeds and dried chilli flakes. Enjoy!