Preheat large, nonstick sauté pan 2–3 minutes on medium-high. Chop vegetables. Place oil and beef in pan; cook 3–4 minutes, stirring occasionally, until browned and 145°F. Remove beef from pan. Add ...
The leftover aspect of this is twofold: first, don’t discard the bits and pieces of pasta at the bottom of a packet, and second, don’t chuck out that leftover cooked pasta.