In a large sauté pan on medium heat add olive oil and butter. Once hot add leeks, salt and pepper. Cook until leeks have softened.
Remove ribs and seeds from the habanero half and cut into thirds. Add to pan and sauté for a few minutes, until fragrant.
Remove stems from collards and stack leaves. Roll up, like a cigar, and cut in 1/2 inch slices. Add collards to pan. Once edges begin to wilt add 1 cup of warm vegetable stock. Continue stirring until collards are half wilted.
Add remaining vegetable stock, cover, lower to low-medium heat and cook for an hour and 15 minutes, or until collards are tender.
In a separate pan on medium-high heat add smoked chorizo and cook until crisp and the fat has rendered. Toss collards with chorizo and plate with raw leek slices for garnish.