Vegetarian dishes that disappoint generally do so for identifiable structural reasons rather than because meat was absent.
The three gaps
Savoury depth, which meat provides through glutamates and browning.
Texture contrast, which meat provides through its own structure.
Satiety, which comes from protein and fat.
Which means a dish that simply omits meat has three deficiencies, and addressing each is a separate decision.
Savoury depth
Available from several sources that many cuisines use routinely.
Mushrooms, particularly dried, which are among the highest natural sources of glutamates.
Tomato concentrated as paste, cooked until it darkens.
Fermented ingredients — soy sauce, miso, fermented bean pastes, aged cheeses where used.
Seaweed, which is used specifically for this in several traditions.
Nutritional yeast, which delivers it directly.
And browning, which produces savoury compounds regardless of the ingredient.
Texture
The gap that is most often unaddressed.
Meat provides chew, and vegetables cooked to uniform softness provide none.
Which means deliberately including something with resistance — roasted vegetables with browned edges, toasted nuts, seeds, crisp fried elements, raw components alongside cooked.
The contrast matters more than any individual texture, which is why a dish with one texture throughout is monotonous regardless of flavour.
Protein and satiety
Pulses, tofu and tempeh, dairy and eggs where used, nuts, seeds and whole grains.
Which need to be present in meaningful quantity rather than as a garnish, since a dish that does not satisfy leads to eating something else afterwards.
Fat contributes as much as protein to satiety and is frequently reduced in vegetarian cooking on the assumption that it should be.
Pulses specifically
Undercooked pulses are one of the most common problems.
They should be genuinely soft, and undercooked ones are unpleasant and harder to digest.
Salt during cooking does not prevent softening, contrary to a persistent belief, and acid does slow it considerably, so tomatoes and vinegar go in after they are tender.
Soaking reduces cooking time and improves digestibility.
Kidney beans specifically must be boiled vigorously before simmering, since they contain a toxin destroyed only by high heat, and slow cooking alone is insufficient.
Tofu
Pressing removes water, which allows browning and improves texture substantially.
Which is the step that converts it from bland and soft to something with character.
Firm and extra firm varieties suit frying and roasting. Silken varieties suit blending and soups.
Freezing and thawing tofu changes its structure, producing a chewier spongier texture that absorbs marinades better.
The imitation trap
Dishes designed around replicating a meat dish generally suffer by comparison.
Which is why the strongest vegetarian cooking comes from cuisines with long vegetarian traditions, where dishes were designed as themselves rather than as substitutions.
Cooking from those traditions produces better results than adapting meat recipes, and it is where the best material is.
Nutritional points
Vitamin B12 is not reliably available from plant sources, and supplementation or fortified foods are recommended for anyone eating no animal products.
Iron from plant sources is absorbed less readily, and vitamin C alongside improves absorption measurably.
Anyone making a substantial dietary change should discuss it with a doctor or dietitian, particularly for children and during pregnancy.
Seasoning through the dish
Vegetables benefit from seasoning at each stage rather than at the end, since they absorb less readily than meat.
Which is why a dish seasoned only at the finish tastes salty on the surface and bland underneath.
Cooking pulses from dried
Tinned pulses are convenient and cost more, and dried ones cooked properly have better texture and take on the flavour of what they cooked in.
Which is a genuine improvement available for very little money and some planning.
Cooking a large batch and freezing in portions removes the planning obstacle entirely.
Nuts and seeds
Toasting transforms them, and untoasted they contribute texture without much flavour.
Which is a two-minute step that is skipped constantly.
They also go rancid, and storing them cool and sealed matters more than for most ingredients.
Where the traditions are
Several cuisines have centuries of vegetarian cooking developed as a primary rather than a substitute cuisine.
Which is where the strongest material is, and cooking from those sources produces better results than any adaptation.
Umami combinations
Certain combinations produce more savoury character than either ingredient alone, an effect that has been measured.
Which is why mushrooms with tomato, or seaweed with fermented soy, taste more than the sum, and it is used deliberately in several cuisines.
Weeknight practicality
Keeping cooked pulses, a good stock, toasted nuts and a few sauces available makes vegetarian cooking as fast as anything else.
Which is where the barrier actually is, since building flavour from scratch each time is slower than cooking meat.
Restaurants
Vegetarian options that were designed as such are generally better than ones adapted by omission.
Which is worth noticing when choosing where to eat, since it indicates whether the kitchen thought about it.