Place Florida orange juice in medium saucepot and reduce volume by ⅔. Reserve 2 Tbsp of reduction for mustard sauce. Combine rest of reduction with breadcrumbs and soak.
Combine Florida orange zest with pork butt, pork fat, soaked breadcrumbs, garlic powder, coriander seeds, fennel seeds, red chili flakes, oregano, salt and black pepper in large bowl. Process through grinder using medium-size grind plate. Mix gently until all ingredients are incorporated evenly. Form into small patties about 2½” in diameter. Refrigerate until ready to cook.
For Florida Orange Mustard: Combine 2 Tbsp Florida orange juice reduction, 1 tsp Florida orange zest, ¼ cup Dijon mustard, ¼ cup whole grain mustard and 2 Tbsp chopped chives. Reserve.
For Grilled Sourdough: Drizzle bread generously with olive oil and grill over medium-high heat on both sides.
Grill sausage patties over medium-high heat until cooked through. Serve with Grilled Sourdough and Florida Orange Mustard on the side.