Make the Sweet Streusel Dust:
Preheat oven to 325°F (165°C) and line a small baking sheet with parchment paper.
Combine flour, brown sugar, cold butter cubes, cinnamon, and salt in a small bowl. Rub butter into dry ingredients with fingertips until mixture forms small, irregular clumps.
Spread on prepared baking sheet and bake 12-15 minutes, stirring halfway through, until golden and fragrant.
Cool completely, then pulse in a food processor until reduced to a fine powder. Store in an airtight container until needed.

Make the Golden Milk Sauce:
Combine coconut milk, whole milk, sugar, turmeric, ginger, cinnamon, cardamom, black pepper, and saffron (if using) in a medium saucepan.
Warm over medium heat, whisking frequently, until steaming and sugar dissolves. Do not boil.
Reduce heat to low and simmer gently for 10 minutes to infuse flavors and thicken slightly.
Remove from heat and whisk in honey and vanilla. Strain through a fine-mesh sieve for extra smoothness if desired.
Keep warm, or cool and gently rewarm before serving.

Prepare the Tropical Fruit:
Combine mango and pineapple in a bowl. Add lime juice, honey, and lime zest and toss gently.
Let macerate at room temperature for at least 15 minutes while you prepare other components.
Just before serving, fold in passion fruit pulp and torn mint leaves.

Prepare the Potatoes:
Peel potatoes and trim into uniform rectangular blocks for even slicing.
Using a mandoline, slice potatoes into very thin rounds approximately 1/16 inch (2mm) thick. Uniformly thin slices are essential for proper puffing.
Immediately place slices in a bowl of cold water to remove excess starch and soak for at least 30 minutes, or up to 2 hours.
Drain potatoes and pat completely dry with clean kitchen towels. Any moisture will cause dangerous splattering and prevent proper puffing.

First Fry (Lower Temperature):
Fill a large, deep heavy-bottomed pot with about 4 inches of oil and heat to 325°F (165°C). Set up a wire rack over a baking sheet nearby.
Working in small batches of 4-5 slices at a time, carefully lower potato slices into the oil.
Fry gently, moving slices around with a spider or slotted spoon, until they just begin to blister and form small bubbles on the surface, 2-3 minutes. They should not brown.
Remove and drain on wire rack. The slices will look pale and slightly blistered. Let rest at least 5 minutes, or up to several hours.

Second Fry (Higher Temperature—The Puff):
Heat fresh oil in a second pot (or strain and reheat the first) to 375-385°F (190-195°C). This temperature differential is what makes the potatoes puff.
Working in very small batches of 2-3 slices, slide pre-fried potatoes into the hot oil.
Immediately begin basting the tops with hot oil using a large spoon—this creates the dramatic puff. The potatoes should inflate into hollow golden pillows within 30-60 seconds.
Once puffed and golden, remove immediately to fresh paper towels. Season lightly with fine sea salt.
Not every slice will puff perfectly; this is normal even for experienced chefs. Aim for 3-4 perfect soufflés per serving.

Third Fry (Optional—Streusel Coating):
Dust warm potato soufflés generously with streusel powder.
For extra crunch and caramelization, briefly re-fry the dusted soufflés for 10-15 seconds in the hot oil to set the streusel coating. Drain on fresh paper towels.

Dress the Mustard Greens:
In a small bowl, whisk together olive oil, honey, and lemon juice.
Toss mustard greens with just enough dressing to lightly coat and season with flaky salt.

To Plate:
Spoon a pool of warm golden milk sauce onto each plate, slightly off-center.
Arrange tropical fruit in and around the sauce.
Place 3-4 potato soufflés on each plate, nestled among the fruit.
Tuck dressed mustard greens around and between the soufflés—they should be visible and integral, not hidden.
Dust with additional streusel powder and powdered sugar.
Garnish with edible flowers and micro herbs if desired.
Serve immediately—soufflés deflate over time.