How to Make It
Follow steps 1 through 4 of Canning Instructions, using five pint-size jars.
Stem jalapeños. Seed and finely dice enough to make 1/4 cup (see Notes). Coarsely chop remaining jalapeños (do not seed); you should have 2 cups. Core and coarsely chop apples; you should have 5 1/2 cups. Stem, seed, and coarsely chop yellow bell peppers; you should have 2 cups.
In an 8- to 10-quart pan, combine coarsely chopped jalapeños, apples, and yellow bell peppers; vinegar; and 1/2 cup water. Bring to a boil over high heat, stirring often; reduce heat and simmer, stirring occasionally, until apples are tender when pierced, about 10 minutes. Gently press mixture through a fine strainer set over a large bowl; discard vegetable mixture or save for other uses. Rinse and dry pan.
Return liquid to pan; add diced jalapeños, red and green peppers, butter (if using), and pectin. Bring to a rolling boil over high heat, stirring often. Stir in sugar; when mixture resumes boiling, stir for exactly 2 minutes if using MCP pectin (1 minute if using Sure-Jell or Ball Fruit Jell). Remove from heat immediately.
Skim and discard any foam from jelly.
Follow steps 5 through 11 of Canning Instructions, leaving 1/4 inch of headspace in each jar and processing jars for 5 minutes (see Notes).
Sunset's Canning Tips:
Add butter to jams and jellies to prevent foam from forming during cooking. If you omit the butter, skim off the foam before ladling jam or jelly into jars. The recipe will yield about 1/4 cup less.
Measure all the sugar into a bowl before beginning the recipe. Many canning recipes call for a large volume of sugar to be added when a mixture is already boiling; measuring ahead simplifies this step and prevents mistakes.
Use a ruler to measure volume. Some recipes call for a mixture to be reduced by a certain amount. To ascertain this easily, insert a clean, wood ruler into the pan before cooking and measure how far up the mixture comes. Then cook as directed until it has reduced by the percentage specified. For example, if uncooked mixture measures 4 inches in pan and recipe says to reduce by half, cook it down to 2 inches.