Peel the potatoes, then grate them into a large mixing bowl using a box grater. I prefer to use the coarsest side (crispier latkes), but my family traditionally uses the finest (cakier latkes). Follow your heart.
Using a strainer, or just by squeezing with paper towels, remove as much moisture as possible from the potato shreds.
Grate the onion into the mixing bowl with the potato, using the finest side of the box grater.
In a separate bowl, grate the pineapple using the coarsest side of the box grater.
Using a strainer, or just by squeezing with paper towels, remove as much moisture as possible from the pineapple shreds. I highly recommend using a strainer over the bowl so you can reserve the pineapple juice for later. It can come in handy when you want to adjust the amount of pineapple flavor coming through in the latkes.
Add the pineapple shreds to the potato-onion mixture.
Add eggs, cayenne, salt, pepper, corn starch, and flour.
You now have a latke batter! It should be wet, but not soup-y. Think pancakes. If there's a puddle of liquid in there, try adding more flour one tsp at a time until things blend a little better. All that said, don't stress too much about it - it's hard to screw up latkes.
If you reserved pineapple juice from your pineapple grating escapades, feel free to add a bit of juice to the latke batter before frying. You can taste the latkes as they come out and adjust from there, too. Basically keep the pineapple juice on deck and add one tbsp at a time if you're looking for a heavier pineapple flavor.
Heat oil in the pan on medium-high. You want about an inch of oil in there -- basically enough to cover the latkes at least halfway.
Once the oil is hot, add the latke batter about 1/4 cup at a time. You can make bigger or smaller latkes but that's a good place to start. I usually fit one or two latkes in my pan at a time, go for as many as you like but don't crowd the pan! It'll make it really hard to flip them.
Fry until the edges start to brown (depending on your oil temp, this takes 2-4 minutes), then flip and fry another 2-4 minutes.
Transfer latkes to paper towel-lined plate(s). If you want, you can taste as they cool and adjust pineapple levels with additional pineapple juice (just remember you're adding more moisture to the batter, so you might need to add a touch more flour to compensate.)
Once latkes are done, throw together your passion fruit sour cream. Here's the recipe: add passionfruit to sour cream. You can make as much as you like -- the golden ratio is one passionfruit per 1/2 cup sour cream. I like to throw in a pinch or two of salt to taste as well. Just whip together with a spoon and enjoy!
Serve latkes warm with a dollop of passion fruit sour cream on top. You can garnish with more passion fruit or a drizzle of pineapple juice if you want to get wild. Enjoy!