Preheat oven to 400.
Heat the duck fat (or olive oil for vegetarian) in a large oven safe skillet (cast iron preferred). Add potato cubes and 1 tsp salt, tossing to coat. Cook until potatoes start to brown, about 5 mintues. Transfer skillet to oven and roast for 20 minutes or until fork tender.
In a blender or small food processor, add the shallots, garlic, mustard, honey, IPA, smoked paprika, pepper and ½ tsp salt, process until well combined, about 2 minutes.
In a large bowl add the potatoes, mustard vinaigrette, green onions, blue cheese, parsley and peas, toss to coat. Serve warm.