Cut potatoes into ¼-inch cubes. Transfer into a pot with enough cold water to completely cover the potatoes. Stir in 1 tablespoon of salt and bring to a boil over high heat. Simmer over medium heat until cubes are tender but still hold their shape, about 15 minutes. Drain potatoes in a colander and set aside.
Heat 1 tablespoon of avocado oil and butter in a skillet over medium heat. Add onion. Cook and stir until softened and translucent, about 5 minutes.
Meanwhile, combine the one teaspoon of kosher salt and garam masala in a small bowl and set aside.
Add serrano pepper, garlic, ginger, spice mix, and the remaining kosher salt to the onions. Cook and stir until mixture is well combined, about 2 minutes. Add peas; cook until heated through and slightly tender, about 3 minutes.
Transfer mixture into a bowl with the potatoes. Add cilantro and lemon juice. Mix with a spatula until filling is well combined, with some potatoes partially mashed.
Spread 6 ounces of the filling in the center of one flour tortilla. Flatten the filling out to about a 3” diameter. Add cheese if desired at a 1 to 1 ratio with the amount of potato mixture (about 6 ounces). Fold the tortilla up and crease over the filling and continue to repeat around the entire tortilla. Repeat with the remaining filling and tortillas.
Heat the remaining avocado oil in a skillet over medium heat. Cook each quesadilla until browned and crispy, 2 to 3 minutes per side. Transfer quesadilla onto your work surface and cut it into half.
Serve with cilantro-lime chutney, fresh cilantro, spring onion, sliced serrano peppers, julienned red bell pepper, and fresh mint.
Cilantro Lime Chutney
In blender or food processor, combine all ingredients; puree until smooth.