Halve and peel onion. Cut one quarter into thin slices and cut remaining into 1/4" dice. Peel and cut potato into 1/2" dice. Mince garlic. Mince mango. Mince cilantro, stems and leaves. In a mixing bowl, add thinly sliced onion, red wine vinegar, 1/4 tsp. salt, and 1/4 tsp. pepper. Marinate at least 10 minutes. While onion marinates, start potatoes.

Place a medium non-stick pan over medium heat and add 1 Tbsp. olive oil. Add potatoes to hot pan, cover, and stir occasionally until completely browned and tender, 6-8 minutes.

Add diced onion, curry, 1/2 tsp. salt, and 1/4 tsp. pepper and stir occasionally until tender, 5-6 minutes. Add peas and garlic and cook until peas are warmed through, 2-3 minutes. Remove from burner.

Place tortillas on a clean work surface. Place half the vegetables, crispy jalapeño (to taste), pickled onion (to taste) (reserve remaining pickling liquid) on each tortilla. Fold sides of tortilla toward center so they nearly touch, then roll bottom edge towards the top, enclosing sides tightly. Lay burrito on its seam. Wipe pan clean and return to medium heat. Add 2 tsp. olive oil and burritos, seam side down, to hot pan. Cook on two sides until browned, 1-2 minutes per side.

Combine mango, cilantro, 1 Tbsp. onion pickling liquid, and a pinch of salt and pepper in another mixing bowl.

Halve burritos if desired. Serve with mango salsa on side.