From America's Test Kitchen Season 8: Pasta and Tomatoes, Reimagined
Splashes of vodka and cream can turn run-of-the-mill tomato sauce into luxurious restaurant fare—or a heavy, boozy mistake. Despite the limited number of ingredients—vodka, cream, red pepper flakes, and tomatoes—we found recipes for penne alla vodka with results that varied widely. Many were absurdly rich (with more cream than tomatoes) and others were too harsh from a heavy hand with the vodka. We wanted to fine-tune this modern classic to strike the right balance of sweet, tangy, spicy, and creamy. To achieve a sauce with the right consistency, we pureed half the tomatoes (which helped the sauce cling nicely to the pasta) and cut the rest into chunks. For sweetness, we added sautéed minced onions; for depth of flavor, we used a bit of tomato paste. We found we needed a liberal amount of vodka to cut through the richness and add “zinginess” to the sauce, but we needed to add it to the tomatoes early on to allow the alcohol to mostly (but not completely) cook off and prevent a boozy flavor. Adding a little heavy cream to the sauce gave it a nice consistency, and we finished cooking the penne in the sauce to encourage cohesiveness.
So that the sauce and pasta finish cooking at the same time, drop the pasta into boiling water just after adding the vodka to the sauce. If possible, use premium vodka; inexpensive brands will taste harsh in this sauce. Pepper vodka imparts a pleasant flavor and can be substituted for plain.