Ingredients
Method
Place mustard seeds in a small saucepan and pour in cool water to cover by ½". Bring to a boil; drain and rinse seeds. Repeat two more times, then transfer seeds to jar.
Bring vinegar, sugar, coriander seeds, salt, and ¼ cup water to a boil in a small saucepan, stirring to dissolve sugar and salt. Pour brine over mustard seeds; let cool. Cover and let seeds sit at room temperature at least 12 hours before serving.
Process ham, maple syrup, hot sauce, Worcestershire sauce, and mustard in a food processor to a paste. Add butter, mayonnaise, and ½ tsp. salt and process until smooth; taste and season with more salt if needed. Transfer to an airtight container and cover with plastic wrap, pressing directly onto surface to prevent a skin from forming. Chill at least 1 hour.
To serve, pack butter into a medium bowl. Drain mustard seeds and spoon half on top of butter. Serve butter with radishes and remaining pickled mustard seeds alongside.
Do Ahead: Ham butter (without mustard seeds) can be made 5 days ahead. Keep chilled.
