Bring a medium pot of boiling water to a boil over medium heat. Season the water with salt, then add the orzo, and cook to al dente. Drain, reserving the cooking water.
Whisk the dressing ingredients in a small bowl until emulsified.
In a skillet, over low heat, melt the butter and add the leeks. Saute for 5 minutes, stirring frequently. Then add the corn and scraped milk from all 4 cobs. Cook for 1 minute and add about 1 cup reserved pasta cooking water. Bring to a simmer and cook until thick and reduced, about 10 minutes, stirring occasionally. Add more pasta cooking water if gets too dry.
Add the orzo and toss to combine. Season with salt, to taste. Transfer the corn and orzo to a serving bowl, garnish with herbs and serve immediately.
