I have found it best to start with a layer of oil in each canning jar before adding your vegetables, as this helps prevent the formation of air bubbles. Also, make sure your vegetables stay completely covered in oil after you start using the preserve. I sometimes keep mine in the refrigerator, taking them out in the morning to rest on the counter and return to room temperature before using them. This helps with the 'crunch' factor.
Though preserving vegetables in olive oil tends to be expensive, as good quality olive oil is not inexpensive, it is a lovely way to put by many vegetables that are wonderful in summer salads, on a pizza, or as side dish.
I particularly like eggplant and peppers preserved in oil. All three items: celery, eggplant and peppers, contribute nicely to salads and antipastos, and the left over oil can be used in all kinds of interesting ways.
PRESERVING CELERY IN OIL
1/4 Cup Kosher Salt
1/8 Cup Raw Sugar
1/3 Cup White Wine Vinegar
1/4 Cup roughly chopped Mint
1/2 Cup Scallion or Ramps with greens, julienned
Olive Oil to Cover
Trim celery sticks and finely slice on the diagonal reserving the leaves and trimmings for soup stocks or seasonings. Follow suit with your onion of choice.
Combine celery, onions and salt, mix well and leave to stand for 30 minutes.
Meanwhile, combine vinegar and sugar in a small heavy-based saucepan and stir over heat until sugar dissolves.
Simmer, uncovered and without stirring, until reduced by one-third and slightly syrupy – you should have about ¼ cup.
Using your hands, gently squeeze away any excess liquid from celery and onions, add to vinegar and let sit for a minute or two.
Pack into wide mouth canning jars, layering with mint.
Split cooled vinegar syrup between jars, top with olive oil. Make sure all vegetables are covered with oil and there are no air bubbles between layers.
Cap tightly and keep in dark, cool pantry or refrigerator until needed.
Here are several recipes from old cookbooks that use the versatile celery in some interesting and vaguely familiar ways.
CELERIS AU LARD
From The Belgium Cookbook; Editor: Mrs. Brian Luck, Published 1815
Take one pound of celery, cut off the green tops, cut the stems into pieces two-thirds of an inch long; put into boiling salted water, and cook till tender. Take one-half pound potatoes, peel and slice, and add to the celery, so that both will be cooked at the same moment. Strain and place on a flat fire-proof dish. Prepare some fat slices of bacon, toast them till crisp in the oven; pour the melted bacon-fat over the celery and potato, adding a dash of vinegar, and place the rashers on top. Serve hot.
The Suffrage Cook Book; Compiled by Mrs. L. O. Kleber, Pittsburgh. The Equal Franchise Federation of Western Pennsylvania, Published 1915
A most delicious relish is made with Roquefort cheese, the size of a walnut, rubbed in with equal quantity of butter, moistened with sherry (lemon juice will serve if sherry be not available), and seasoned with salt, pepper, celery salt, and paprika; then squeezed into the troughs of a dozen slender, succulent sticks of celery.
This is a very appropriate prelude to a dinner of roast duck.