Chess Opening Theory/1. e4/1...c5/2. d4/2...cxd4/3. Nf3
This aims to transpose into normal lines. After Nxd4, a normal open Sicilian will be reached. If black tries to prevent this with 3...e5, White will reach a good Smith-Morra with 4.c3. Therefore, black does best to allow Nxd4.