It was about as big as a White Castle slider patty. It was crowned with the bright yellow of poached quail egg and a magenta flower. It was a calf's brain, and I was about to eat it. My brain quest began early—several weeks before, when I was trying to think of the most ridiculous offal I could consume. Testicles came to mind, but I could not find a restaurant that served them. So I turned to brains instead, locating KO Prime (90 Tremont St., 617-772-0202), a swanky steakhouse that served cerebellum. My friend Will and I arrived early, hopping off the Park Street T stop and making a short walk to the dimly-lit steakhouse. We seated ourselves on some stools near the window and contemplated the menu. Alas, the only calves brains on the men was presented as a quiche, with pancetta, hazelnuts, and fiddlehead tomme. If I was going to be eating brains, it might as well be distinctively brainy. I wanted to be able to distinguish one lobe from another. I wanted to see all the nooks and crannies which once held the simple, grass-eating thoughts of a calf awaiting slaughter. Fears of mad cow disease would not stop me. (Swine flu, maybe.) In Spain, they make brain burritos. I wanted, however, to be converted at the high end. I decided to go out on a limb and asked our waiter if the chef could make something more “brainy” than the quiche. He came back with good news—the chef would create a special appetizer just for us. The chef came out to personally present us with the creation, a brain with a poached quail egg, on top of a layer of fava beans and morels, and anchored with a layer of toasted brioche. He poured a tiny pitcher of spring pea soup at the base. This was no normal, Fear Factor gross-out brain. This was haute brain. The waiter came over for a peak and declared, “Hell yeah!” It was time. My knife cut through the gray matter (actually, it looked like a turkey burger) like it was room temperature butter. I speared that, a bit of brioche, and dipped it in the soup. I put it in my mouth. Strangely, bliss. Brain has very little flavor on its own. It is soft and melts in your mouth like a particularly good cut of fat. The flavor came from the other elements of the dish, with the brioche crucial in giving it any textural heft. Will and I enjoyed ourselves thoroughly, marveling at how well each element of the dish worked together. Our only criticism was that the brioche disappeared too quickly. By the end, I ate a large chunk of brain without supporting actors, feeling a little queasy since it was a particularly stringy, evocative portion. I suggested that the chef put bull testicles on the menu. “Come back in a month,” the manager told me, after reporting the chef’s excitement. He promised he would personally send me an e-mail. I’ll be back.