Vegetables are generally a bit more complicated than fruit to freeze. Unlike fruit, vegetables keep on ‘living’ in the freezer and become tough and tasteless. To prevent this you need to blanch or precook them. This slows down the activity of the enzymes.
The fresher the vegetables the better the results will be. Prepare the vegetables as you usually would and put similar sizes together. Boil water in a large saucepan and add the vegetables (it is easier to take them out again if you have them in a wire basket or something similar). Bring the water back to the boil and blanch the vegetables for 1-4 minutes depending on the size of the pieces. Remove the vegetables and tip into icy cold water to prevent overcooking and maintain good colour. Drain and dry vegetables in a tea towel to prevent them sticking together. To free flow, spread them on a baking tray and freeze until solid then put into plastic bags, remove air and seal.
For green vegetables, generally it is until they turn bright green. Green beans and celery cut into 2.5 cm pieces will take about 2 minutes. Carrots and courgette can be sliced or in strips and also take about 2 mins. Peas will take just over a minute. Broad beans can take 2-4 minutes depending on the size. Broccoli and cauliflower will depend on the size of the florets but smaller ones will only take a couple of minutes. Cabbage can be shredded (1 min) or cut into wedges (3 mins). Brussels sprouts can be blanched whole or cut in half. Corn can be blanched on the cob for 4 mins and then removed for freezing.
Leafy greens only take a minute to blanch. I take handfuls and squeeze them into a small balls and free flow them – this makes it easy to handle and cook later. Herbs can be blanched and frozen whole or pressed into ice cube trays. I like to make pesto and freeze that in ice-cube trays or small pots. These can be easily added to soups and casseroles for instant tasty flavouring.
For potatoes, kumara, pumpkin etc bake or roast them about 3/4 of the time you usually would – then freeze.
Some vegetables are actually fruit so can be frozen as is if you want. Tomatoes are a good example – if you don’t have the time or inclination to deal with them at the peak of harvest you can simply wash them and put them in the freezer whole in bags. You can process them later – if you plunge the frozen tomatoes into boiling water for a minute or so the skins can be removed easily. The down-side is that they take up lots of room in the freezer.
Capsicums or peppers can also be frozen without processing. I usually cut them in half and remove the seeds. I often buy lots when they are cheap and freeze them for use over winter. I also like to grill/char a few and remove the skins and seeds before freezing. These are great to add to hummus or to give a lift to tomato soup.