The phrase "generous teaspoon" means more than the usual amount of something that can fit on a teaspoon. It suggests being very generous or giving a bit extra. Full definition
Put 1 generous teaspoon avocado mixture in one corner of wrap. (californiaavocado.com)
Fill cavity in each half or wedge with 1 clove, 1 teaspoon honey, 1 generous teaspoon chopped raisins and a few walnut pieces. (guidosfreshmarketplace.com)
For every cup of tea, 3 fresh, peeled, deseeded lychees 1 c. hot water 1 generous teaspoon of tea (use loose leaf if you can, as those can be reboiled) (princesstofu.com)