Remove tough stems, especially on mature spinach. Tear large leaves into pieces. Submerge in a large bowl of cold water, swish well, lift out, and repeat two or three times until the water runs clear. Drain in a colander. Pre-washed baby spinach needs just one rinse. No need to dry completely — a little residual moisture helps it wilt evenly. Measure out your garlic, oil, salt, and pepper before you start cooking, since cook time is very short.

Set a pot over medium heat and add a drizzle of olive oil. If using garlic, stir it for 2 to 3 minutes until just golden, then remove or leave it as you prefer. Add spinach in batches, tossing and waiting for each handful to wilt before adding the next. Season with salt and pepper, cover, and cook for 2 to 3 minutes. Baby spinach needs only 1 to 2 minutes of tossing before covering; mature leaves may need the full 3 to 5 minutes total. Drain off any excess liquid through a colander before serving.

Spinach is done when all leaves have fully collapsed and turned deep, vibrant green — tender but not mushy or grey. Pull it from the heat the moment the last leaves soften; overcooking happens fast. Drain excess liquid in a colander, then briefly return to the pot to heat through if needed. Do not leave spinach sitting in its liquid or it turns watery and dull. Serve immediately with olive oil, lemon juice, or balsamic vinegar. Toasted pine nuts work well as a garnish. Wilted spinach does not hold, so serve straight from the pot.