You can make enough canna-oil for one burger without much smell pretty easily, although it won't look pretty. Which you can then simply just spread on your burger bun like a marijuana sauce. [not my recipe/writing] Prepare in a teaspoon enough hash/kief/finely grinded bud. Add a small amount of cooking oil into the spoon so that it covers all. Then heat the spoon with a lighter for about 2 minutes. just keep stirring it on the spoon till roasting. The cooking oil will start to bubble and become cloudy with a dark color. The oil extracts the THC from the hash and 'brings it to the surface'. When all the hash has dispersed into the oil, spread it on what you want.