It really is hard to find safe stuff for them to do when you're cooking, and they just want to see/touch everything! It's easier to let them help with baking- measuring, whisking, mixing, smearing butter into the pan, putting cupcakes liners in, etc.
As for cooking, DD likes to smash garlic and "chop" herbs with her play kitchen knives, stir dressings and marinades, more measuring, tearing lettuce for salad. We've had one of these kitchen helper step stools for about a year and a half so that she can see what I'm doing without being picked up (it stays on the opposite side of the island from where I generally work). it seems to help if she can at least see what I'm doing and ask a million questions about it.
ETA: As part of the constant questions phase, I also keep up a running commentary with her, what I'm doing, why I'm doing it, asking what she thinks is next, what veggie/fruit I'm chopping, etc. It's like a cooking show for preschoolers, lol.