Traditional steamed tamales certainly require a little spice to give the corn masa some character, but the emphasis should remain on the sweet meat filling, whether shredded chicken, pork or beef. For that reason, go for peppers with a mild, sweet flavor rather than the hotter options, which will only overpower the end product.
Clean and Spicy
Ripe, green serrano peppers, usually around 3 inches long, give a clean, fresh zip to the tamale without bullying the overall flavor. Milder than the eye-watering habanero, which is best in pepper sauces, but stronger than the jalapeno, which lends itself to stuffing, serranos offer an acceptable level of heat. And this can be toned down further by removing the seeds.
Sweet and Smoky
California chiles, also known as Anaheim chiles, are among the mildest peppers. You can slice them into crunchy slivers when they are ripe and green to use raw, or toast the ruby red dried version briefly to draw out the oils, before blending with a little water or stock to make a sweet, smoky pureed salsa. Pureeing works too for chili ancho, the dried poblano, but you will first need to char and remove the skin, and remove the seeds. The young green chili is much milder than the ripe, red version, but both have a sweet flavor with a fruity finish.