Slice off the stem end of the parsnips; peel with a vegetable peeler.
Use a mandolin or a chef knife to cut the parsnips into rectangular planks approximately 1/4-inch thick.
It can be dangerous to cut a round parsnip into planks with a chef knife (if it rolls, you can cut yourself); make life easier by creating a flat edge; cut a long, thin piece from the side of the parsnip and discard it; roll the parsnip so that the flat side is facing down on the cutting board; now, when cutting the 1/4-inch planks, the parsnip will sit flat and much less likely to cause a cut.
Set a large skillet over high heat; add just enough canola oil to cover the bottom of the skillet.
When the oil begins to lightly smoke, add the parsnips; cook for 2 to 3 minutes, stirring regularly.
A nice sear may result on all sides of the parsnips; a little char is ok.
Do not overcrowd the skillet; cook the parsnips in batches, if needed, adding more oil as necessary.
When the parsnips are nicely seared, transfer to a rimmed baking sheet and season with salt and freshly ground black pepper.
Remove the skillet from the heat and deglaze the pan with the white wine; use a wooden spoon to scrape any flavorful bits from the bottom of the skillet; set the skillet over medium heat and cook until the wine is nearly fully reduced.
Add the rosemary, butter, and maple syrup; stir to combine.
Add the parsnips back into the skillet with the sauce; cook, over medium heat, for 1 to 2 minutes, stirring regularly.
The parsnips should be nicely coated with the sauce.
Taste a parsnip; adjust with more salt as necessary; do not overcook the parsnips; they shouldn’t be too soft or mushy; they should be just cooked through, like an al dente bite of perfectly cooked pasta.
When happy with the taste and texture of the parsnips, remove from heat and serve.
