Seeing red a matter of taste

Should guacamole have chopped tomatoes and onions in it, or just chillies and lemon juice? How long can it keep before it goes dark?

- Meredith

It can have whatever you want in it. I tend not to add tomatoes or onions (too harsh), but I do add lime or lemon juice (and zest - but go easy) as it prevents it from discolouring. Another way to prevent guacamole going brown is to put it into a container, press Glad Wrap over the top, and seal it.

Can you solve the debate in our family about whether, when you chargrill vegetables on the barbecue, you toss them in oil (in a ziplock bag) and then put them on the grill, or is it better to just oil the grill and put the raw veges straight on?

- Bryce Simpson

I tend to brush oil on sliced veges rather than take the scattergun approach of tossing in oil, which can be wasteful. You can also use no oil at all, but drizzle with extra virgin olive oil once off the grill - there are many ways and all have merit.

When I make tomato pasta sauces, do I really need to skin and seed the tomatoes or can I get away with putting the cooked sauce through a mouli?

- Anabelle Brinks

Keep all parts of the tomatoes - they contain lycopene which is considered excellent in the diet. You can pass the finished sauce through a mouli, but there's no need to get too fussy.