Select a substitute based on your recipe needs—poblano for roasting/stuffing, cubanelle or banana for cooking or raw use, jalapeño or bell + cayenne for heat control.
Prepare substitutes as needed: roast poblanos and bell peppers; dice or slice cubanelle and banana peppers; remove seeds from jalapeños to adjust heat.
Apply the recommended substitution ratios, increasing volume for thinner peppers and reducing quantity for hotter ones.
Incorporate substitutes into your dish; for heat adjustments, add cayenne early when using bell peppers.
Taste and adjust seasoning or heat as needed to achieve desired flavor and texture.