Finely dice the yellow onion, plum tomato, and serrano pepper, removing the pepper seeds if you prefer a milder heat.
Heat the extra virgin olive oil in a large non-stick skillet over medium-high heat.
Add the diced onion and serrano pepper to the skillet, sautéing for 3 to 4 minutes until the onion becomes translucent and fragrant.
Stir in the pre-cooked ground beef and diced tomatoes, seasoning with sea salt and black pepper.
Cook for 2 minutes to allow the tomatoes to soften and the beef to warm through completely.
In a small bowl, crack the eggs and whisk them thoroughly until the yolks and whites are fully combined.
Reduce the skillet heat to medium and pour the whisked eggs over the beef and vegetable mixture.
Using a spatula, gently fold the eggs into the mixture, stirring occasionally until the eggs are just set and fluffy.
Remove the skillet from the heat and garnish the scramble with freshly chopped cilantro before serving.