When chef Brian De Souza and Sydney Younggreen first opened The Regular last summer, they bit off more than they could chew. The couple had big dreams for their 6,500-square-foot space at 1432 Market St., originally dividing it into three concepts: The Regular, an a-la-carte, fine-dining restaurant; The Guest, a 22-seat speakeasy restaurant; and El Mercado, a daytime deli. The Regular’s menu is inspired by chef and owner Brian De Souza’s Peruvian heritage through locally sourced ingredients.