How Does Too Much Oil in Indian Mughlai Food Makes It Tasty?
Oil is a great non-polar solvent and will dissolve many flavor molecules that don't dissolve well in water.  “Like dissolves like”.  For instance, capsaicins from chili peppers, zingerone from ginger, piperine from black pepper, and many others, dissolve sparingly in water but well in oils.

Not just hot flavors, either - limonene (citrus), carvone (S and R forms, from spearmint and caraway), and other essences are non-polar.

Once dissolved, they're mobile and easier to taste.