Sardines don't take long to cook, but pressure cookers come in handy when you need to prepare them in quantity. Sardines have undergone a resurgence in popularity, but you still don't find them market-fresh very often unless you live near the coast. You can't store sardines, so when you find them fresh, seize the moment. Buy as many as you can, invite some friends over and use a pressure cooker to cook them quickly. You can use the time you save to choose a crisp white wine to pair with them, and a night of simple pleasure will ensue.
Add a cup of water, stock, wine or a combination thereof to the pressure cooker. Pressure cookers need liquid to function, so use it as a chance to incorporate flavor. Sardines don't need anything complex, but a bit of wine or stock kicks their flavor up a bit.
Add herbs and spices to the liquid. Simple is better, so limit yourself to 1 or 2 fresh herbs and spices maximum.
Season the sardines inside and out with kosher salt and freshly ground black pepper. Stuff the sardines with a couple of thin lemon slices, if desired.
Add the sardines to the pressure cooker and place it on the stove. Set the heat to high.
Secure the lid on the pressure cooker when the liquid starts to boil. Watch the pressure valve on the lid as the steam inside builds, and lower the heat to medium when the valve stem reaches the 10-psi marking.
Cook the sardines for 3 to 5 minutes on low pressure. Use the low end of the time scale if cooking 4 or 5 sardines, and the high end if cooking 10 or more. Place the pressure cooker in the sink and run cold water over it.
Take the lid off the pressure cooker when it unlocks. Serve the sardines while hot and with a tomato sauce, if you made one.