Wash and dry Meyer lemons. Trim off ends and slice the fruit in half from to top to bottom.
Using a sharp paring knife, cut out the pithy center core of each lemon half and remove seeds. Reserve both the pithy cores and seeds, as these will later be our pectin source.
When all lemons have been trimmed, slice the halves into thin half moons.
Place Meyer lemon slices into a glass or plastic bowl and cover with two cups of water.
Gather up the reserved seeds and pith and place them into the center of a cheesecloth square. Tie bundle up tightly to prevent seeds from escaping. Add this bundle to the bowl where the lemon slices are soaking. Cover and set aside.
While the lemon slices soak, wash strawberries and chop them well. Place them in a glass or plastic bowl and add the sugar. Stir to combine and cover.
Let both the lemons and the strawberries sit for at least an hour and up to three hours. Stir the strawberries once or twice if possible, to help the sugar draw out their liquid.
When you’re ready to cook the marmalade, first set up your canning pot. Place four half pint jars in a pot fitted with a shallow rack. The pot must be able to hold them fully submerged with at least an inch of water over top and an inch of space to allow the water to boil.
Place lids in a small saucepan of water and set over low heat.
Pour the lemons, their water, the strawberries and sugar into a large, wide, non-reactive pan that holds at least five quarts. Bring to a boil and cook over medium-high heat for 30-40 minutes, stirring regularly.
Marmalade is done when it reaches 220° F and passes the plate test.
Funnel finished marmalade into prepared jars. Wipe rims, apply lids and rings and process in a boiling water canner for 10 minutes.
When time is up, remove jars from canner and let them cool on a folded kitchen towel.
When jars are cool enough to handle, remove rings and check seals. Any unsealed jars should be refrigerated and used promptly.