I think so, from context. I don't think "meal" is being correctly used here. "Main course" or "entree" would be correct. "Main part of the meal" would also be correct. The writer mentions "starter," which is part of a meal, and "dessert," which is also part of a meal, so I feel sure that "main meal" is supposed to mean the main part of the meal.

Yes, you are correct, they are using this to mean 'main course'. I.e. as a starter 'before' their main meal...

There is an expression "main meal of the day" which means whichever meal is the largest. For most people it is dinner, but some people (and maybe some doctors) say that it is not good to eat a lot before going to sleep, so it is better to have the main meal of the day be lunch. In your excerpt, however, as everyone points, out I think this should be "main course" not "main meal", although it is certainly true that people can eat avocados before dinner.

Main meal and main course are the same in this context. Main meal could also mean the biggest meal you eat during the day, which would usually be dinner (and for some people, lunch).