Place sliced onions and jalapeños in a medium-sized glass bowl.
Combine white vinegar, water, sugar, salt, black peppercorns, bay leaf, garlic, and coriander in a small saucepan. Cook over high heat until mixture boils.
Pour brine over onions and jalapeños.
Cover and refrigerate at least 24 hours.
Melt butter in medium saucepan over medium heat.
Add onion and sauté 5-8 minutes, or until onions are translucent.
Add flour, stirring constantly, for 3-5 minutes. Do not allow mixture to brown.
Add cream, salt, white pepper and nutmeg.
Cook over medium heat, stirring constantly, 5 minutes, or until simmering.
Reduce heat to low and simmer, stirring occasionally, 20-25 minutes, until mixture is thick and coats the back of a spoon.
Add hot sauce.
Slowly add cheese, stirring constantly, 3-5 minutes, until cheese melts and is creamy.
Add diced jalapeño peppers. Keep warm until ready to serve.
Heat canola oil in a large sauté pan over medium for 5 minutes, or until oil is shimmering.
Carefully add potatoes.
Cook potatoes over medium heat, stirring occasionally, 6-8 minutes, until potatoes are golden and cooked through.
Add remaining vegetables and cubed smoked beef brisket.
Cook 3-5 minutes, until softened. Season with salt and pepper.
Evenly divide burnt ends brisket hash among plates.
Top with white cheddar cheese fondue.
Garnish with pickled jalapeño peppers.