Pre-prepped foods are also a lifesaver in situations like this.
For the recent Japanese menu, I pre-made about 1.25 gallons of dashi stock (which would go into the miso soup, the okonomiyaki batter, and the tempura dip), about a gallon of pork-and-chicken bone broth (for the ramen), the pork-infused shoyu tare for the ramen (the strained, leftover soy-sake-mirin-sugar-garlic-scallion mixture the chashu pork simmered in), and the soy marinated soft-boiled eggs. TBH, I could have also premade the yakisoba (I just got lazy the day before and took a nap instead of cooking more) and pre-chopped some veggies which would have saved me even more time.
This meant my main focuses when I got in where veggie chopping for soups, tempura, and curries, sauteing the chicken teriyaki, and deep-frying the pork cutlets while I went about placing out and recombining the precooked stuff for service. My new rice cooker just got to hang out and handle the white rice all by itself, and the curry coming from pre-made curry bricks mostly (aside from caramelizing the onions and par-cooking the carrots and potatoes in vegetable stock for extra flavor) made that a dead-simple recipe to assemble.
Due to some issues I ran into, this still didn’t work perfectly (the okonomiyaki just didn’t come together till 2/3 of the guests had already eaten; we didn’t have enough fryer-space for the tempura), but it helped a lot.
In less detail, for the burgers-and-al-pastor bday party, the al pastor marinade, guacamole, rice, and beans were all done ahead of time, and tbh, I wish I had gotten to the party early enough to pre-shape all the burgers so I didn’t panic and send the hostess out for unnecessary extra beef an hour into things.
So for a larger gathering, think about what can be done and held ahead of time. Obviously most of your served-cold (or room temp) sides should be done ahead–potato salad, actual salad, breads, etc. Condiment and topping layouts should be largely set or passed off to a friend or family member. Consider seeing if you can pre-cook the corn and the vegan sausages and then hold them to temp in a 250F oven (I am betting neither is in much danger of over-cooking).
Also, while this is outside of my experience, a LOT of folks who grill for groups I know, including some here on the forums, are gaga over sous vide. That way you can pre-cook the steaks and salmon directly to desired internal temp, hold them there in large batches indefinitely, and then just de-bag and sear when it’s time to serve. Enormous time-saving, and still fits under the umbrella of pre-cooking!
Also, this is an area where appetizers and drinks make you look like an excellent host. While I was tackling the Japanese food, my friend Megan was keeping the crowd at bay with a veritable wall of chips, dips, and veggie snacks. Having someone on mixed drink duty is awesome. Having a quick-prep appetizer you can serve fresh–say, cheese sticks or something from the deep fryer, which pushes out high quantities quickly–while you cook longer-timed stuff is also good.
Heck, helpers helped me at the Japanese thing–I set two girls on an unfortunately slow-cooking electric griddle to the task of the fried rice and the hibachi vegetables (which were prepped very similarly) after I had setup the mise in place for both and shown them an example batch to start with.
edit: this post is largely written from the perspective of not limiting an absurd menu to something more feasible, because I am an absurd human. reducing total variety is also entirely valid and people are still gonna be hella grateful to you for cooking :)
