A TALE OF TWO PERSONALITIES

there's a stoat hiding in that last one

A sincere and good-faith question is never a reason to fight =)

Yes, it does matter.

Something like bell pepper or tomato (soft tissue, lots of water) is going to cook a lot faster than something like potato or turnup (firm tissue, not much water).

If you had the same-sized piece of bell pepper and potato, and cooked them for the same amount of time, either you'll have a well-cooked bell pepper and an undercooked potato.... or a well-cooked potato and a really overcooked bell pepper.

This is why many recipes which have both firm vegetables like turnip/potato, and soft-flesh vegetables like tomato and bell pepper will ask you to add the firm-flesh ones first, and cook them for a bit, and THEN add the soft-flesh veggies, so that they'll all arrive at their 'well-cooked' state at the same time.

But if you have teeny tiny pieces of potato (diced) and larger chunks of bell pepper (chopped), and start cooking them at the same time in the same pan... because the potato pieces have a lot of surface area exposed to the heat, relative to their total size, they'll cook at about the same speed as the much larger bell pepper.

So you'll have a dish of combined diced potato and chopped pepper which will start at the same time, AND be finished all at the same time!

--

If you're just asking for a soup where you add EVERYTHING at the same time, and just boil away... the cut-shape influences the cook time.

Pieces with a lot of surface area relative to their size (diced, matchstick, sliced, minced) means you don't need to cook it as long. Bigger pieces (chopped) need more total cook time for the heat to penetrate.

Sometimes, recipe-makers will just prefer a certain size and shape of ingredients because it influences the mouthfeel of taking a bite, or because it's visually appealing.

--

Chop: Big rough cuts. Each chunk is somewhere between the size of your whole thumb and your first thumb joint. 1-inch by 1-inch

Diced: Smaller cuts. Each piece is roughly the width/length of your first pinkie joint. 1cm by 1cm.

Minced: Cut into teeeeny tiny pieces! Minced garlic is a good reference. Each piece will be about the size of a red pepper flake. About 2mm by 2mm.

Cubed: This is on shape not size. Make it into even square shapes. Cubed potatoes tend to be 'chop' size, while onion cubed tends to be dice size.

Sliced: Again, shape not size. This describes parallel cuts made to create pieces that are quite thin, but still wide or long. Pepperoni slices.