Hey there, I need to use up some carrots celery and onions, any ideas besides a soup?

Mince all those things and add them to a pan of ground beef. Then proceed to make Bolognese sauce. Which you then can use in spaghetti/lasagna/gnocchi....

Make a stuffing and freeze the portions. It's a great side dish throughout the year. And if you use sage, you'll be reminded of Thanksgiving. Sage dressing with carrots, onions and celery is my favorite part of Thanksgiving dinner.

Make chicken/veggie/beef stock & freeze in 2 cup portions.

Pickled carrots.
Savory carrot cake from the Paris Baker.
https://www.ft.com/content/261de2d4-6d69-11e1-b6ff-00144feab49a
Grilled celery (as a side dish for meat or chicken).

You could add the onions and celery but I would just save that for tuna salad

My italaian family cooks everything and I mean everything with olive oil and garlic , extra carrots make a great cold fresh salad, just boil them aldente ( not too mushy)cool them add extra virgin olive oil if u have it or reg olive oil , chopped garlic to taste, parsley , pepper and salt, sooo yummy and healthy

I made a batch of this veggie bouillon on Heidi Swanson's site: http://www.101cookbooks.com/archives/homemade-bouillon-recipe.html minus the celery as I'm allergic. It keeps in the freezer and adds surprising depth to sauces, soups etc. just when you need a little oomph.

Giardiniera. One of my favorites. I make Lidia Bastianich's recipe, which is fresh and clean. You might need to make a run for some other veggies.

It's almost the holy trinity in a classic Cajun rue, with a substitution of carrots for green bell pepper; try a gumbo with the before-mentioned rue.

I take leftover or old-ish vegetables, and add a cut tomato or two. I microwave them to soft. Then I purée them and freeze them. I usually use them to make ragu (spaghetti sauce). I start the water for pasta, and heat some oil for sautéing chopped garlic and onion. Sauté meat next, until brown. During all this I defrost the veggie purée, and add it with enough tomatoes, canned, fresh, oculus or paste to make a pleasing sauce. By the time the pasta is finished you have the sauce.

You could make a side dish of roasted vegetables with them. You'd need to cut the carrots smaller than the rest because they take longer to cook. I like to prep any vegetables for roasting ahead of time by cutting them appropriately and putting them into a sip lock bag with olive oil and seasonings for several hours, then dumping onto a half sheet pan and roasting in a 400 degreeF oven for (for this combination) about 25 minutes.

Sautée them, add cooked lentils or another bean, throw in other complimentary leftovers from your fridge, and dress with a light vinaigrette.

Chop them up and put them in ziplock bags and put them in the freezer.
Use as a base for soups and stews or addtions to tomato sauces.

Another option is to make celery sticks, carrot sticks. Use with pimento cheese as a dip. Or as a side dish with 'chicken fingers' and ranch or blue cheese dressing.

Vegetable stew: start browning onions, carrots, celery, sweet potatoes, white potatoes, turnips, any other vegetables you have in a big heavy pot using butter and oil or bacon drippings or whatever you wish. A couple of cloves of garlic, some shredded cabbage, and any vegetable leftovers should go in too, and if you wish some corn and lastly a small can of stewed tomatoes. Season with salt, pepper, paprika, and Worcestershire sauce, and if you wish to cover with breadcrumbs and grated cheese and finish it in the oven, that is good too, though not necessary.

Vegetable stew: start browning onions, carrots, celery, sweet potatoes, white potatoes, turnips, any other vegetables you have in a big heavy pot using butter and oil or bacon drippings or whatever you wish. A couple of cloves of garlic, some shredded cabbage, and any vegetable leftovers should go in too, and if you wish some corn and lastly a small can of stewed tomatoes. Season with salt, pepper, paprika, and Worcestershire sauce, and if you wish to cover with breadcrumbs and grated cheese and finish it in the oven, that is good too, though not necessary.

Vegetable stew: start browning onions, carrots, celery, sweet potatoes, white potatoes, turnips, any other vegetables you have in a big heavy pot using butter and oil or bacon drippings or whatever you wish. A couple of cloves of garlic, some shredded cabbage, and any vegetable leftovers should go in too, and if you wish some corn and lastly a small can of stewed tomatoes. Season with salt, pepper, paprika, and Worcestershire sauce, and if you wish to cover with breadcrumbs and grated cheese and finish it in the oven, that is good too, though not necessary.

These are your basic aromatics for almost any type of meat braise. Sweat them down in oil and/or butter. Your meat might be beef, pork shoulder, lamb or even goat. I do like goat. After that, some stock and your seasonings.

A rich-earthy beef stew--cubed chuck steak, Italien Roma canned tomatoes, tomato paste, home/made or canned beef broth OR add some green bell pepper and make a jambalaya with andouille and chicken or seafood with shrimp and scallops