Heat the extra virgin olive oil in a medium non-stick skillet over medium-high heat.
Add the finely diced yellow onion and red bell pepper to the skillet, sautéing for 3-4 minutes until the vegetables are tender and translucent.
Add the lean ground beef to the skillet, breaking it up with a spatula, and cook until completely browned and no pink remains.
Stir in the minced garlic and cook for 1 minute until fragrant.
Lower the heat to medium-low and pour in the tomato puree and coconut aminos.
Add the yellow mustard, smoked paprika, chili powder, sea salt, and black pepper, stirring well to combine all the flavors.
Allow the mixture to simmer for 5-7 minutes, stirring occasionally, until the sauce has thickened and coated the beef beautifully.
While the beef simmers, lightly toast the whole wheat slider buns in a separate pan or toaster oven until golden.
Divide the smoky beef mixture evenly between the two toasted slider buns and serve immediately while hot.