You could use switches, example:
Switch 1: Bread
Switch 2: Lettuce
Event: If 1 and 2 are on and you press an event, say for instance, a sandwich icon in the menu you will start cooking it and you recieve one sandwich.
You could go a bit further and use Variables to add a bit of "chance" to it. You can basically make a variable of "If Sandwich is cooking, what are are the odds of it working?", so Variable 1: Sandwich cooking can triggered when you hit the sandwich icon (Along with the Bread and Lettuce switches). When this is done, you can goto the Variable side of things, so "If Variable 1 is on, use random variable numbers for the probability of sandwich cooking succeeding", after this point you can do what you want with the numbers, make it random as shown here:
(https://rmrk.net/proxy.php?request=http%3A%2F%2Fi36.photobucket.com%2Falbums%2Fe9%2FTezuka101%2Fvar.png&hash=d331539d0841493155f98e90d95a3d474f18e6a3)
Change both zeros to the numbers of your liking.
After this, you can use this Conditional Branch:
<>Branch if Car [xxxx:Sandwich Cooking] is y or more/less
<>Message: Failed!
<>
: Else Handler
<>Message: SUCCESS!
<>Change Items: 1 Sandwich Add
<>
: End
<>
This can seem confusing, but that is the basics.
Just replace "xxx" with switch number and "y" with the number you you want.
For the graphic side of things, you will need to do that yourself.
How bout you try using items instead of switches, like so (make by Tezuka and i helped)
@>Text: Do you want to cook with the available ingredients?
@>Show Choice: Yes, No
: When [Yes]
@>Text: What would you like to cook?
@>Show Choice: Sandwich, Nevermind
: When [Sandwich]
@>Conditional Branch: [Bread] in inventory
@>Conditional Branch: [Lettuce] in inventory
@>Change Item: [Bread], -1
@>Change Item: [Lettuce], -1
@>Control Variables: [Sandwich cooking] = Random No. (1...10)
@>Play SE: "042-Knock03", 80, 100
@>Wait: 5 frame(s)
@>Play SE: "042-Knock03", 80, 100
@>Wait: 5 frame(s)
@>Play SE: "042-Knock03", 80, 100
@>Wait: 5 frame(s)
@>Play SE: "042-Knock03", 80, 100
@>Wait: 30 frame(s)
@>Conditional Branch: Variable [0003:Sandwich cooking] >= 5
@>Play ME: '007-Fanfare01', 100, 100
@>Text: SUCCESS! (Adquired 1x Sandwich)
@>
:Else
@>Play ME: '005-Defeat', 100, 100
@>FAILURE!
@>
:Branch End
@>
:Else
@>Text: Not enough ingredients.
@>Change Item: [Sandwich], +1
:Branch End
: When [Nevermind]
@>
:Branch End
:When [No]
@>
:Branch End
@>
It's put like in XP but I'll work in 2K3.