My first dinner at the Bruce pop-up happened last month out of desperation. I’d planned with a friend to arrive extra early at one of L.A.’s current impossible-to-book restaurants in hopes of snagging a couple of unreserved seats. Then: ugh. I’d forgotten I had a late afternoon doctor’s appointment. By the time I was free, we were scouting possibilities in different neighborhoods. “Wilde’s isn’t taking any more names for the night.” “At Hermon’s. Quoted a 90-minute wait for the bar.” “Now at Vandell. About the same thing.” It dawned on me: My colleague Stephanie Breijo had written the previous week about a pop-up formed by three chefs — Brittany Ha, Hannah Grubba and Alex Riley — banding together after they’d lost their jobs at Horses, which closed suddenly in December. Bruce is the name of Ha’s infant son. The trio had taken over the tiny open kitchen at Cafe Triste in Chinatown three nights a week through February. This is the L.A. pop-up to try right now The reservations had been snapped up for the …