Place the potatoes into a pot with enough cold water to completely submerge the potatoes. Add 3 tablespoons of salt, place the pot over high heat and bring the water to a boil. Reduce the heat to medium low and continue cooking the potatoes on a gentle simmer until fork tender, about another 30 to 40 minutes. 

Preheat the oven to 450 degrees.

Drain the water and return the dry potatoes into the pot over medium heat. Shake the pot every so often to dry out the potatoes, for about 3 to 5 minutes. 

Transfer the potatoes onto a parchment lined baking sheet. Firmly smash each potato with the bottom of a heavy cup. Add the shallots, olive oil and salt. Stir to coat all the potatoes and shallots. Transfer the baking sheet into the oven and roast the potatoes until golden brown, about 35 to 40 minutes.

Place the cooked potatoes and shallots into a heatproof bowl. Add the cilantro, parsley, white wine vinegar, jalapeños, and lime zest (if using) and stir to combine.

Transfer the dressed potatoes onto a platter and immediately serve hot.