Kate McKinnon is unpacking her lunch onto the New York City sidewalk. “If I could talk to everyone on this street, I would,” she says. “I’m always on the hunt for people—something I like about them or something that hooks me about them.” It’s the one o’clock lunch rush on a Thursday, and we are squatting on a six-inch ledge that separates a row of hedges in Rockefeller Center from 49th Street, balancing takeout containers on our knees. Tourists step around us on their way to 30 Rock without recognizing the Saturday Night Live standout in their midst. “I swear I’m not doing this so you have something interesting to write in your piece,” she says. “It’s just—where else is there to sit?”

McKinnon joined SNL in 2012 and now, at 34, is its longest-serving female cast member. She has built a career on the sweet eccentricity of her characters: Hillary Clinton unable to mask her longing for validation; Justin Bieber playing at a sexual persona he hasn’t yet grown into; Ruth Bader Ginsberg high on her own badassery. These renditions—precise, uproarious, tender—have earned her two Emmys, an army of devotees, and a rising career in film. Despite the quantity of material she produces each week for SNL, she never falls flat. It doesn’t matter who she’s playing or how deep in her archive you go, she’s like the hot sauce of TV: Put her in anything, and it gets better. I wanted to know how she manages that level of consistency. Does she have some kind of system?

“So many YouTube videos,” McKinnon says. “Me, alone in my office, talking back to YouTube videos.” She mulls the question, breaking down the order of operations in her mind: “I like to devise axioms and notice patterns of what works and what doesn’t so I can codify those into little rules I can use. If someone has a vocal tic or an accent, it’s so much easier to hook into something. It always starts with the way they talk, and then you add the layer of their energy.” A basic resemblance is usually necessary, though she’s been known to stretch that guideline (see: her leering Rudy Giuliani). “Then it all depends on what they’ve done that week,” she says. “They can’t just be someone who did something five months ago. It’s got to be à la minute.”

At the core of any impression is what sketch comedians call “the game.” The game is the unexpected conflict buried at the center of a person. “With Jeff Sessions it’s his joy and impishness versus his being a political figure with a very important job,” McKinnon says, suppressing a smile. “That’s the genesis of a game, which you can then heighten: the juxtaposition between someone who is buttoned up and someone who is emotional.”