Combine the potatoes, liquid smoke, garlic, a nice pinch of salt and a few grinds of pepper in a large pot; add water to just cover. Bring to a boil, then reduce the heat and simmer until the potatoes are fork-tender, 15 minutes. Drain, then rest the colander over the empty pot to dry the potatoes. Once cooled slightly, quarter the larger potatoes and halve the others. Put in a large bowl. Discard the garlic.
Char the bell peppers directly over a medium flame on a gas burner, rotating, until the peppers are black. (Or broil the peppers, rotating, until charred.) Transfer the charred peppers to a resealable plastic bag and close; let steam 5 minutes. Once cool enough to handle, remove the seeds and charred skin and chop the peppers.
Cook the bacon in a large skillet over medium heat, stirring, until crisp, about 8 minutes. Remove with a slotted spoon to a plate, leaving the fat in the pan. Add the vinegar, sugar, mustard, paprika, a pinch of salt and a few grinds of pepper to the still-hot pan; simmer until the sugar and salt dissolve, 2 minutes. Add the potatoes and toss until they soak up the vinegar mixture.
Return the potatoes to the bowl. Add the peppers, bacon, parsley and scallions; toss.