Prepared in 15 minutes or less.
Over high heat, place a large pot of water and season with a dash of salt. Add spaghetti and cook to al dente according to package directions. Save a couple of mugs full of starchy cooking water before draining the pasta. Reserve.
While the pasta is boiling, place a large skillet over medium-high heat. Add 2 tbs of olive oil. Add the scallion whites and chopped garlic to the pan and cook until tender, about 2 minutes.
Add one mug full of the reserved pasta-cooking water and the cooked pasta to the pan and bring up to a bubble.
While that’s heating up, in a small bowl, place the egg yolks and whisk to break them up.
Add remaining cooking water to the egg yolks while whisking constantly to heat them up.
Reduce the heat under the skillet to medium and add the egg mixture to the pasta, stirring constantly with tongs to incorporate.
Add the tangerine juice, zest, Parmigiano Reggiano, some salt and pepper to the pan, and simmer until thickened, about 2 minutes. Reserve warm.
Meanwhile, in a medium sauté pan, heat the remaining olive oil.
Season each side of the scallops with salt and pepper.
When the pan is smoking hot, add the scallops. Sear each scallop on one side until golden brown, about 2 to 3 minutes. Turn each scallop over and sear the other side until golden, about 2 to 3 minutes.