In a large skillet (12-inch), brown the beef and onion. Add the garlic and cook for about a minute. Drain the meat.: The moment the ground beef hits the hot skillet you should hear a lively sizzle and smell that rich, beefy aroma as the surface browns. As the onion softens it releases a sweet perfume that marries with the meat. I press and stir occasionally to ensure even browning and to create those tiny crisped bits that add texture. When the meat is no longer pink and the onion is translucent, add the minced garlic and keep the pan moving for about a minute until the garlic's edge rounds out and its fragrance blooms. Drain the meat to avoid an oily dip, because excess fat will make the sauce greasy. A common error is overcrowding the pan, which causes steaming instead of browning, so use a wide skillet and brown in batches if needed.
Add the enchilada sauce to the meat and stir until combined. Bring mixture up to medium-high heat.: When you pour the red enchilada sauce in, the aroma shifts to a tangy, slightly smoky note that tells you the dish is coming together. Stir thoroughly so the sauce coats every bit of ground beef , creating a cohesive, glossy mixture. Bring it to medium high so it simmers gently, allowing flavors to concentrate without evaporating all the liquid. You want a lively surface simmer, not a rolling boil, because too aggressive heat can toughen the meat and dull the sauce's brightness. Watch for splatter and reduce heat if it pops, and avoid simmering so long that the sauce thickens beyond the ideal dipping consistency.
Sprinkle the cheddar cheese evenly over the mixture. Reduce heat to low. Cover and let the cheese melt.: As you scatter the shredded cheddar cheese across the surface, you will see it begin to soften almost immediately, then transform into ribbons and pools. Reducing the heat to low is key so the cheese melts gently, becoming glossy and elastic instead of grainy. Covering the skillet traps steam and speeds melting, while preventing the top from drying out. Listen for a subdued, steady hiss as steam helps the cheese become silky. The wrong move here is cheating with high heat, which can cause the cheese to separate and become oily rather than cohesive.
Garnish with cilantro and serve with tortilla chips for dipping.: Once the cheese has melted into an inviting, molten blanket, the final touches add contrast. A sprinkle of chopped cilantro brings a citrusy brightness that lifts the heavy flavors, while a spoonful of sour cream smooths spicy edges and sliced olives add a salty, briny counterpoint. Serve with sturdy tortilla chips so each scoop delivers a mix of crunchy texture and warm, cheesy filling. Be mindful that adding garnishes too early will make them wilt or lose their color, so add them right before serving for the best visual and textural contrast. Also, avoid serving with flimsy chips that break under the weight of the dip.