Combine equal parts of ground chile de arbol and salt on a saucer and coat the rim of a Collins glass.
Fill with ice and set aside.
In a shaker, muddle the cucumber, bell pepper and lemon juice.
Add the tequila, agave nectar, bitters and ice and shake.
Strain into the prepared glass.
Top with ginger beer.
Garnish with a red bell pepper and cucumber slice.