Place cubed potatoes in a pot, cover with cold water, add 1/2 tsp salt, bring to a boil and cook until tender (about 10–12 minutes). Drain and set aside to steam-dry for 5 minutes.

Temper spices & cook aromatics

Heat 2 tbsp vegetable oil in a skillet over medium heat. When hot, add mustard seeds and cumin seeds; let them pop (~30 seconds). Add chopped onion and sauté until translucent and starting to brown at edges, about 6–8 minutes. Stir in minced garlic and ginger and cook 1 minute more.

Spice the onions

Add turmeric, ground coriander, garam masala and red chili powder to the pan; toast spices for 20–30 seconds to bloom their aroma.

Combine with potatoes

Add the drained potatoes to the skillet. Gently mash about one-third of the potatoes with the back of a spoon to create a cohesive filling. Stir to coat potatoes with the spiced onion mixture. Sprinkle 1.5 tsp salt (adjust to taste) and cook together 3–4 minutes to allow flavors to meld.

Finish filling

Remove from heat, fold in chopped cilantro and 1 tbsp lime juice. Taste and adjust seasoning. Keep warm while you prepare shells.

Puffy Taco Shells (Fried)

Make dough

In a mixing bowl, whisk together 2 cups all-purpose flour, 1 tsp baking powder and 1/2 tsp salt. Add 1/2 cup plain yogurt and 1 tbsp oil. Mix, then add warm water a tablespoon at a time until a soft, slightly tacky dough forms (about 3–4 tbsp). Knead 3–4 minutes until smooth. Cover and rest 20–30 minutes.

Portion and roll

Divide dough into 8 equal pieces (for 8 tacos). Roll each piece into a smooth ball, then roll out on a lightly floured surface to a 5–6 inch round, about 1/8 inch thick. Keep rolled rounds covered under a towel to prevent drying.

Heat oil and fry

In a wide, deep skillet or medium pot, heat 3 cups vegetable oil to 350°F (175°C) or until a small piece of dough sizzles and rises quickly. Fry one round at a time: gently slide round into hot oil and press lightly with a slotted spoon — the dough should puff into a balloon. Flip once and fry until golden on both sides, about 30–45 seconds per side. Remove and drain on paper towels. Shape into taco form while still warm by folding over a wooden spoon handle or by draping over the edge of a bowl; they will hold shape as they cool.

Make-ahead note

Fried shells are best used within 1 hour for maximum puff; you can keep warm in a low oven (200°F/95°C) for up to 30 minutes but will lose some crispness over time.

Chutneys & Sweet Yogurt

Sweeten yogurt

Whisk 1 cup plain yogurt with 2 tsp powdered sugar (or honey), 1/2 tsp roasted cumin powder and 1/4 tsp salt until smooth and slightly aerated. Taste and adjust sweetness/salt to balance with chutneys.

Prepare chutneys

If using store-bought chutneys, give them a quick stir. If homemade, ensure tamarind chutney is thick and slightly sweet-tart; cilantro-mint chutney should be vibrant and slightly spicy. Transfer chutneys to squeeze bottles or small bowls for easy assembly.

Assembly & Garnish

Assemble puffy tacos

Hold a warm puffy shell and spoon about 2 to 3 heaping tablespoons of the curried potato filling into the center. Drizzle about 1 tablespoon each of tamarind chutney and cilantro-mint chutney over the potatoes. Add 1 to 2 tablespoons of the sweetened yogurt on top.

Add crunch and finish

Scatter about 2 tablespoons of sev over each taco, add a few slices of soaked red onion if using, and sprinkle with fresh cilantro leaves. Serve with a lime wedge to squeeze over before eating.

Serving suggestion

Serve immediately so shells remain crisp. Provide extra chutneys, yogurt and sev on the side for guests to adjust to taste.