Heat skillet over high heat for several minutes then add oil.
When oil is nearly smoking hot add tomatoes and sear over very high heat for 3 minutes.
Reduce heat to medium and add garlic.
When garlic turns golden, add Balsamic, sugar, red pepper, oregano or marjoram.
Meanwhile, bring a large pot of salted water to boil and cook spaghettini to al dente.
In another skillet with cover, bring half a cup of water to boil add sausage links, cover and steam for five minutes.
Remove from heat and slice sausages on the bias.
Dump water and add 1 Tbs. oil to skillet and quickly sear sausage pieces over high heat.
Add sausage to green tomato sauce.
When pasta is nearly Al Dente, add to green tomato sauce in skillet, toss, and cook until pasta is tender.
Add 1/2 cup of pasta water to sauce, toss and serve with grated Pecorino Romano.
Working with a single heavy skillet under high heat transforms firm, unripened tomatoes by caramelizing their natural sugars while the added sugar tempers the sharp acetic acid of the vinegar. Searing the fruit at near-smoking temperatures for three minutes develops deep Maillard compounds before the garlic goes in, preventing the aromatics from burning prematurely. Deglazing the pan with six tablespoons of balsamic vinegar releases the browned tomato fond, creating a complex reduction that clings tightly to the starch of the pasta. Steaming the sausage links in half a cup of water prior to slicing ensures the meat cooks through evenly without drying out its interior fat. Finishing the dish by combining the al dente spaghettini directly inside the sauce with half a cup of starchy pasta water emulsifies the oil and acid into a cohesive coating. Pecorino Romano provides a salty, dry umami contrast that cuts through the rich pork proteins and the sweet, tangy reduction.