It's hard to figure out where the heat comes from in the duck spring rolls ($8.95) at O'Rourke's Steakhouse (4611 Montrose, 713-523-4611). Perhaps it's the complex, bright red dipping sauce made from red chiles, garlic, wine vinegar and a dash of sugar. No, that's not it. Then it must come from somewhere in the extra-crispy rolls themselves. Like Vietnamese egg rolls, they're rolled tightly in a thin wrapping, then cut on the diagonal. Deconstruct the filling and -- aha! -- you'll discover that the finely sliced duck breast has been mixed with sautéed jalapeño peppers. The reason it creeps up on you is that sautéing moderates the heat. Mystery solved.