Bring 1 cup water to a boil in a saucepan. Add the lime gelatin and stir until the gelatin dissolves. Pour into a liquid measuring cup and mix in the orange liqueur and tequila.
Meanwhile, cut the limes in half lengthwise and scoop the flesh out of both halves. Place each half in the cups of a mini muffin tin and pour the gelatin mixture into each half. Place the muffin tin in the fridge until set.
Cut each half into 2 wedges, sprinkle with salt and shoot!