From the walkthrough:
Use only ingredients that you have enough of. Don't exhaust your supply.
Check the journal-documents.
Seasoned salad: Combine water spinach + palm oil.
Cake batter: Combine water + flour + (sugar, honey or maple syrup) + egg.
Tart: Make the batter as above + fruit (oranges, trulca or blue dessert). Place in kiln.
Seafood: Cook fish, crawfish or mussel in kiln.
I think Leonard likes seafood especially. He might not like the salad so much (that's more to Mina's taste).