This makes me wonder beyond salad dressing and granola:

What else is low effort to make and vastly better or cheaper than store-bought?

@jonobie

Syrups and sauces - from liquid sugar and coffee flavours to raspberry coulis and chocolate syrup.

Soups and stocks. Often just put ingredients in a pot and heat through.

"hot dish", casserole, or whatever your regional term: a 1-pot melange usually involving a protein, a starch, vegetables &/or fungi, and a flavorful sauce/gravy. Process is usually baked or slow-cooking.

Best skill to practice & improve: making rice. Easy to do, hard to perfect.