Heat the olive oil in a medium skillet over medium-high heat. Stir in the tomatoes and onions and cook for 5 minutes until the onions are translucent and the tomatoes start to soften.
Stir in the garlic and cook for an additional 1 minute until fragrant.
Remove the chorizo from the casing and add it to the skillet. Using a wooden spoon or spatula, crumble it up into small pieces and saute for 8 minutes until fully cooked through. If the chorizo is extra fatty and lets out a lot of grease (it likely will), feel free to drain off any excess fat.
In a separate bowl, whisk together the eggs. Pour them into the skillet and let them cook for about 30 seconds. Then, continue gently stirring until the eggs are just cooked through.
Remove the pan from the heat, and season with salt and black pepper to taste. Garnish with queso fresco and cilantro, and serve immediately.