Place diced potatoes in boiling water and cook until soft.
In the mean time fry the ground beef in a pan over medium high heat.
When the meat is nearly cooked add the onion and continue cooking until the onions are soft and browned.
Add the chili powder, coriander, cumin, and pepper, cooked potatoes and minced garlic.
Also add a little water to your meat to moisten it and pick up some of the bits of meat from the bottom of the pan, it only needs to be about a 1/4 of a cup.
Starchy Binding
Substituting sweet potatoes for standard russets alters the structural integrity of picadillo by introducing excess sugars that caramelize too rapidly in the skillet. Standard potatoes contribute starch that binds the loose ground beef granules together without scorching. Boiling the diced potatoes separately ensures they soften completely before encountering the salty pan environment, preventing surface dehydration that halts interior cooking.
Spice Bloom Dynamics
Introducing chili powder, coriander, cumin, and black pepper directly to the rendered beef fat dissolves fat-soluble aromatic compounds efficiently. Fat acts as a thermal conductor, carrying heat rapidly to extract volatile oils from the spices within 30 to 45 seconds of direct contact. Minced garlic added simultaneously prevents acrid sulfur compounds from forming, a risk if garlic is subjected to dry heat without moisture.
Moisture Control and Deglazing
Pouring a quarter cup of water into the hot skillet dissolves fond stuck to the metal surface, reincorporating proteins into the meat mixture. Steam generated by this liquid hydrates the spices and softens the finely diced onions without boiling the beef. Potatoes added at this stage absorb excess free liquid, yielding a dense filling suitable for taco tortillas.